KR20240017896A - Electrode composition, electrode sheet for all-solid-state secondary battery, and all-solid-state secondary battery, and electrode composition, electrode sheet for all-solid-state secondary battery, and method for producing the all-solid-state secondary battery - Google Patents

Abstract

An electrode composition that realizes excellent dispersion characteristics and strong binding properties of solid particles while enabling a reduction in the content of polymer binder, an electrode sheet and all-solid-state secondary battery for an all-solid-state secondary battery using this electrode composition, and an electrode composition for an all-solid-state secondary battery A method for manufacturing an electrode sheet and an all-solid-state secondary battery is provided. The electrode composition is an electrode composition containing an inorganic solid electrolyte, an active material, a polymer binder, and a dispersion medium. The polymer binder is dissolved in the dispersion medium, and the adsorption rate to the active material is 20% or more and is a polymer that has an adsorption rate greater than the inorganic solid electrolyte. It includes binder A and a polymer binder B that is dissolved in a dispersion medium and has an adsorption rate of 20% or more to the inorganic solid electrolyte and is greater than the rate of adsorption to the active material.

Description

Electrode composition, electrode sheet for all-solid-state secondary battery, and all-solid-state secondary battery, and electrode composition, electrode sheet for all-solid-state secondary battery, and method for producing the all-solid-state secondary battery

The present invention relates to an electrode composition, an electrode sheet for an all-solid secondary battery, and an all-solid secondary battery, and a method for producing an electrode composition, an electrode sheet for an all-solid secondary battery, and an all-solid secondary battery.

In an all-solid-state secondary battery, the negative electrode, electrolyte, and positive electrode are all made of solid, and can greatly improve safety and reliability, which are problems with batteries using organic electrolyte solutions. It is also said that longevity can be achieved. Additionally, the all-solid-state secondary battery can have a structure in which electrodes and electrolytes are directly arranged in series. Therefore, higher energy density becomes possible compared to secondary batteries using organic electrolyte solutions, and application to electric vehicles or large storage batteries is expected.

In such an all-solid-state secondary battery, materials forming the active material layer (also referred to as an electrode layer) include inorganic solid electrolytes and active materials. These inorganic solid electrolytes, especially oxide-based inorganic solid electrolytes and sulfide-based inorganic solid electrolytes, are expected to be electrolyte materials with high ionic conductivity close to that of organic electrolyte solutions.

As a material forming the active material layer of an all-solid-state secondary battery (also referred to as an active material layer forming material or electrode composition), the above-mentioned inorganic solid electrolyte, active material, and further binder (binder) are dispersed or dissolved in a dispersion medium ( For example, a slurry composition) has been proposed, and among them, a material using two types of binders in combination has also been proposed. For example, Patent Document 1 includes a solid electrolyte, an active material, a non-polar solvent, a first binder insoluble in the non-polar solvent, and a second binder soluble in the non-polar solvent, and the first binder and the second binder Composite materials with different SP values are described.

Japanese Patent Publication No. 2015-244428

When forming an active material layer with a solid particle material (inorganic solid electrolyte, active material, conductive additive, etc.), the active material layer forming material and the binder used therein may be used to improve battery performance of an all-solid-state secondary battery (e.g. For example, various characteristics are required from the viewpoint of reducing battery resistance and improving rate characteristics or cycle characteristics. For example, in the case of active material layer forming materials, the dispersion stability that stably maintains the good initial dispersibility of the solid particles (also called solid particles) immediately after preparation (initial dispersibility and dispersion stability are collectively referred to as dispersion properties) .) is required to be excellent. In addition, the active material layer formed from the active material layer forming material is required to have adhesiveness (adhesion) that firmly binds (adheres) the solid particles. On the other hand, since the binder has poor ionic conductivity and electronic conductivity, it is required to reduce its content in the active material layer forming material and the active material layer from the viewpoint of suppressing an increase in battery resistance.

As described above, the material for forming the active material layer is required to have both conflicting properties, such as reducing the binder content and realizing solid particle dispersion properties and strong binding properties.

The object of the present invention is to provide an electrode composition that realizes excellent dispersion characteristics and strong binding properties of solid particles while enabling a reduction in the content of the polymer binder. In addition, the present invention aims to provide an electrode sheet for an all-solid-state secondary battery and an all-solid-state secondary battery using this electrode composition, and a method for manufacturing the electrode composition, an electrode sheet for an all-solid-state secondary battery, and an all-solid-state secondary battery. .

In conventional active material forming materials, even if improvements such as changing the mixing order are made, a group of solid particles containing an inorganic solid electrolyte, active material, etc. is assumed to be a uniform mixture, and these solid particles are dispersed and bound as a whole. Shiki was selecting a binder.

However, as a result of the present inventor's intensive study of the active material layer forming material, the binder usually increases its interaction with the active material in conjunction with increasing the interaction with the inorganic solid electrolyte. Therefore, even if the solid particle group containing the inorganic solid electrolyte and the active material is assumed as a complete mixture and the binder used in combination with it is examined, it is difficult to achieve both the dispersion characteristics and binding properties of the solid particle group and the reduction of the binder content. came to the conclusion that it was not enough. Therefore, as a result of further investigation, the present inventor has found that, in the active material layer forming material containing the active material, the inorganic solid electrolyte, and the dispersion medium, the solid particle group containing the inorganic solid electrolyte and the active material is not necessarily a mixture, but The inorganic solid electrolyte and the active material were assumed to be different solid particle groups, and the idea was to improve the binder for each solid particle group. Based on this idea, the present inventors used a combination of binders that can be preferentially adsorbed to the active material and binders that can be preferentially adsorbed to the inorganic solid electrolyte among the binders that dissolve in the dispersion medium, thereby reducing the total binder content. While reducing the amount, each of the active material and the inorganic solid electrolyte can be stably dispersed in the active material layer forming material not only immediately after adjustment but also over time (due to excellent dispersion characteristics), creating an active material layer in which each of the active material and the inorganic solid electrolyte are firmly bound. I found out what can be formed. In addition, it was found that this active material layer forming material can realize a low-resistance active material layer in which solid particles are strongly bound, and that an all-solid-state secondary battery incorporating this active material layer can realize low resistance and excellent battery performance. .

The present invention was completed through further examination based on these findings.

That is, the above problem was solved by the following means.

<1> An electrode composition containing an inorganic solid electrolyte having conductivity for metal ions belonging to group 1 or 2 of the periodic table, an active material, a polymer binder, and a dispersion medium,

polymer binder,

Polymer binder A, which is a polymer binder that dissolves in a dispersion medium and has an adsorption rate of 20% or more to the active material in the dispersion medium and is greater than the adsorption rate to an inorganic solid electrolyte;

An electrode composition comprising polymer binder B, which is a polymer binder that dissolves in a dispersion medium and has an adsorption rate of 20% or more to an inorganic solid electrolyte in the dispersion medium and is greater than the adsorption rate to an active material.

<2> The electrode composition according to <1>, containing a conductive additive.

<3> The electrode composition according to <1> or <2>, wherein the polymer forming at least one of the polymer binder A and the polymer binder B contains a component having a functional group selected from the following functional group group (a).

<Functional group (a)>

Hydroxy group, amino group, carboxy group, sulfo group, phosphoric acid group, phosphonic acid group, sulfanyl group, ether bond, imino group, amide bond, imide bond, urethane bond, urea bond, heterocyclic group, aryl group, carboxylic acid anhydride energy

<4> Any one of <1> to <3>, wherein the polymer forming the polymer binder A has at least one bond among a urethane bond, a urea bond, an amide bond, an imide bond, and an ester bond in the main chain. The electrode composition described in .

<5> The electrode composition according to any one of <1> to <4>, wherein the polymer forming the polymer binder B is obtained by polymerizing a monomer having a carbon-carbon unsaturated bond.

<6> The content of polymer binder A is 1.5% by mass or less based on 100% by mass of solid content of the electrode composition,

The electrode composition according to any one of <1> to <5>, wherein the content of polymer binder B is 1.5% by mass or less based on 100% by mass of solid content of the electrode composition.

<7> An electrode sheet for an all-solid-state secondary battery having an active material layer formed using the electrode composition according to any one of <1> to <6>.

<8> An all-solid-state secondary battery comprising a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order,

An all-solid-state secondary battery, wherein at least one of the positive electrode active material layer and the negative electrode active material layer is an active material layer formed using the electrode composition according to any one of <1> to <6>.

<9> A method for producing the electrode composition according to any one of <1> to <6> above,

A process of preparing an active material composition containing an active material, polymer binder A, and a dispersion medium;

A process of preparing a solid electrolyte composition containing an inorganic solid electrolyte, polymer binder B, and a dispersion medium;

A method for producing an electrode composition, comprising the step of mixing an active material composition and a solid electrolyte composition.

<10> A method for producing an electrode sheet for an all-solid-state secondary battery, comprising forming the electrode composition according to any one of <1> to <6> into a film.

<11> A method for manufacturing an all-solid-state secondary battery, wherein the all-solid-state secondary battery is manufactured through the manufacturing method described in <10> above.

The present invention can provide an electrode composition that realizes excellent dispersion characteristics and strong binding properties of solid particles while enabling reduction of content. Moreover, the present invention can provide an electrode sheet for an all-solid-state secondary battery and an all-solid-state secondary battery having an active material layer composed of this electrode composition. Additionally, the present invention can provide an electrode composition, an electrode sheet for an all-solid-state secondary battery, and a method for producing each of the all-solid-state secondary batteries.

1 is a longitudinal cross-sectional view schematically showing an all-solid-state secondary battery according to a preferred embodiment of the present invention.

In the present invention, the numerical range indicated using “~” means a range that includes the numerical values written before and after “~” as the lower limit and upper limit. In addition, in the present invention, when explaining the content of components, physical properties, etc. by setting a plurality of numerical ranges, the upper and lower limits forming the numerical range are the specific upper and lower limits written before and after "~" as the specific numerical range. The combination is not limited, and the numerical range can be formed by appropriately combining the upper and lower limits of each numerical range.

In the present invention, the expression for a compound (for example, when calling it "compound" at the end) is used to include not only the compound itself, but also its salt and its ion. In addition, it is meant to include derivatives in which some changes have been made, such as by introducing substituents, within the range that does not impair the effect of the present invention.

In the present invention, (meth)acrylic means one or both of acrylic and methacrylic. The same applies to (meth)acrylate.

In the present invention, for a substituent, linking group, etc. (hereinafter referred to as a substituent, etc.) for which substitution or unsubstitution is not specified, this means that the group may have an appropriate substituent. Therefore, in the present invention, even if it is simply described as a YYY group, this YYY group includes aspects that have a substituent in addition to aspects that do not have a substituent. This has the same meaning for compounds that do not specify substitution or unsubstitution. A preferable substituent includes, for example, the substituent Z described later.

In the present invention, when there are a plurality of substituents, etc. indicated by a specific symbol, or when a plurality of substituents, etc. are specified simultaneously or alternatively, it means that each substituent, etc. may be the same or different from each other. In addition, even if it is not specifically explained, this means that when a plurality of substituents, etc. are adjacent, they may be connected to each other or condensed to form a ring.

In the present invention, polymer means a polymer and has the same meaning as a so-called high molecular compound. Additionally, a polymer binder (also simply referred to as a binder) refers to a binder composed of a polymer, and includes the polymer itself and a binder composed (formed) including the polymer.

In the present invention, a composition containing an inorganic solid electrolyte, an active material, and a dispersion medium and used as a material (active material layer forming material) for forming an active material layer of an all-solid-state secondary battery is referred to as an electrode composition for an all-solid-state secondary battery, or simply an electrode composition. do. On the other hand, a composition that contains an inorganic solid electrolyte and is used as a material for forming the solid electrolyte layer of an all-solid-state secondary battery is called an inorganic solid electrolyte-containing composition, and this composition usually does not contain an active material.

In the present invention, the electrode composition includes a positive electrode composition containing a positive electrode active material and a negative electrode composition containing a negative electrode active material. Therefore, either or both of the positive electrode composition and the negative electrode composition may be simply referred to as an electrode composition, and either or both of the positive electrode active material layer and the negative electrode active material layer may be simply referred to as an active material layer or electrode active material. Sometimes it is called a layer. In addition, either one of the positive electrode active material and the negative electrode active material, or both together, may be simply referred to as an active material or an electrode active material.

[Electrode composition]

The electrode composition of the present invention includes an inorganic solid electrolyte (SE) having conductivity for metal ions belonging to group 1 or 2 of the periodic table, an active material (AC), a polymer binder (PB), and a dispersion medium (D). It contains. And, this polymer binder (PB) includes a polymer binder A that is dissolved in the dispersion medium (D) and satisfies the following adsorption rate, and also a polymer binder B that is dissolved in the dispersion medium (D) and satisfies the following adsorption rate. It includes. One type of polymer binder A and polymer binder B may each be contained in the electrode composition, and two or more types may be contained.

Polymer binder A: The adsorption rate for the active material (AC) in the dispersion medium (D) is 20% or more, and is also greater than the adsorption rate for the inorganic solid electrolyte (SE).

Polymer binder B: The adsorption rate for the inorganic solid electrolyte (SE) in the dispersion medium (D) is 20% or more, and is also greater than the adsorption rate for the active material (AC).

The electrode composition of the present invention, which contains a combination of polymer binder A and polymer binder B as a polymer binder (PB) for the inorganic solid electrolyte (SE) and the active material (AC) in the dispersion medium (D), has a total content of polymer binder. Even if the (especially the total content of polymer binders A and B) is reduced, the inorganic solid electrolyte (SE) and active material (AC) can be stably dispersed not only immediately after adjustment but also over time (dispersion characteristics are excellent), and When forming an electrode composition, the inorganic solid electrolyte (SE) and the active material (AC) can be firmly brought into close contact. Therefore, by using this electrode composition as an active material layer forming material, a low-resistance active material layer in which the inorganic solid electrolyte (SE) and the active material (AC) are firmly bound together, and further an all-solid material with low resistance and excellent battery characteristics A secondary battery can be realized.

The details of the reason are not yet clear, but it is thought as follows.

The electrode composition of the present invention includes a polymer binder A that exhibits higher adsorption (preferentially adsorbed) to the active material (AC) than the inorganic solid electrolyte (SE), and higher adsorption to the inorganic solid electrolyte (SE) than the active material (AC). It contains polymer binder B, which exhibits (preferentially adsorbs). In this electrode composition, the preferential adsorption amount of polymer binders A and B to the active material (AC) or inorganic solid electrolyte (SE) is determined by the adsorption rate of each binder, the difference in adsorption rate, the content of each component, and the dispersion medium (D ), and it cannot be unilaterally determined because it varies in the preparation method or conditions of the electrode composition, but polymer binder A, which exhibits the above-mentioned adsorption rate, is often present adsorbed to the active material (AC), and polymer binder B is It is presumed that many of them exist adsorbed on inorganic solid electrolytes (SE). Therefore, polymer binder A can increase the dispersibility of the preferentially adsorbed active material (AC), and polymer binder B can increase the dispersibility of the preferentially adsorbed inorganic solid electrolyte (SE). In addition, both polymer binders A and B are dissolved in the dispersion medium (D), broadening the molecular chain, and effectively suppressing (re)aggregation or precipitation by repelling the adsorbed active material (AC) or inorganic solid electrolyte (SE) from each other. I think it can be done (the dispersion characteristics are excellent). In addition, the adsorption and dispersion states of the polymer binder and the active material (AC) or the inorganic solid electrolyte (SE) described above are maintained even when forming a film of the electrode composition, and as a result, in the formed active material layer, the active material (AC) or the inorganic solid electrolyte (SE) is maintained. The solid electrolyte (SE) is thought to be strongly bound while maintaining a highly dispersed state. In addition, by using polymer binders A and B together, the active material (AC) and the inorganic solid electrolyte (SE) can be adsorbed separately to disperse and bind, thereby dispersing and binding the active material (AC) and the inorganic solid electrolyte (SE). The amount of polymer binder required for processing can be reduced. Therefore, the inhibition of the construction of the ion conduction path and the electron conduction path by the polymer binder (PB) can be suppressed. In addition, since the active material layer can be formed while maintaining the above-described highly dispersed state, it is thought that it is difficult for the inorganic solid electrolyte (SE) and the active material (AC) to be unevenly distributed, thereby suppressing the non-uniformity of the contact state in the active material layer. do.

In this way, when the active material layer is formed using an electrode composition that realizes excellent dispersion characteristics and strong binding properties of the inorganic solid electrolyte (SE) and the active material (AC) while enabling a reduction in the polymer binder content, the inorganic solid electrolyte (SE) It is possible to form an active material layer in which the inorganic solid electrolyte (SE) and the active material (AC) are strongly bound while suppressing localization of the (SE) and the active material (AC) and ensuring direct contact. Therefore, it is believed that an all-solid-state secondary battery incorporating this active material layer has low resistance (exhibits high ionic conductivity and high electronic conductivity) and exhibits excellent battery characteristics such as rate characteristics.

In the electrode composition, the polymer binders A and B are dissolved in the dispersion medium (D) and adsorbed to the active material (AC) or the inorganic solid electrolyte (SE) or interposed between solid particles, thereby forming the active material (AC) or the inorganic solid electrolyte (SE). It is thought that it exhibits the function of dispersing (SE) in the dispersion medium (D). On the other hand, the polymer binders A and B are thought to function as binders that adsorb to the active material (AC) or the inorganic solid electrolyte (SE) and bind them together in the active material layer. In addition, the polymer binders A and B are preferentially adsorbed to the active material (AC) or the inorganic solid electrolyte (SE), respectively, but may be adsorbed to the inorganic solid electrolyte (SE) or the active material (AC).

Here, the adsorption of polymer binders A and B to the active material (AC) or inorganic solid electrolyte (SE) is not particularly limited, but is not limited to physical adsorption, as well as chemical adsorption (adsorption by chemical bond formation, electron transfer). adsorption, etc.) are also included.

In addition, the polymer binders A and B may also function as a binder that binds the current collector and solid particles.

Since such an electrode composition exhibits the above-mentioned excellent properties, it can be preferably used as a forming material (constituent layer forming material) of an electrode sheet for an all-solid-state secondary battery and an active material layer of an all-solid-state secondary battery. In particular, it can be preferably used as a material for forming a positive electrode active material layer.

The electrode composition of the present invention is preferably a slurry in which an inorganic solid electrolyte and an active material are dispersed in a dispersion medium.

The electrode composition of the present invention is preferably a non-aqueous composition. In the present invention, the non-aqueous composition includes forms in which the water content (also referred to as water content) is preferably 500 ppm or less in addition to forms that do not contain moisture. In a non-aqueous composition, the moisture content is more preferably 200 ppm or less, more preferably 100 ppm or less, and especially preferably 50 ppm or less. If the electrode composition is a non-aqueous composition, deterioration of the inorganic solid electrolyte can be suppressed. The water content represents the amount of water contained in the electrode composition (mass ratio with respect to the electrode composition), and is specifically the value measured using Karl Fischer titration after filtration through a 0.02 μm membrane filter.

Hereinafter, the components that the electrode composition of the present invention contains and the components that it can contain will be described.

<Inorganic solid electrolyte (SE)>

The electrode composition of the present invention contains an inorganic solid electrolyte (SE).

In the present invention, an inorganic solid electrolyte is an inorganic solid electrolyte, and a solid electrolyte is a solid electrolyte capable of moving ions therein. Since organic substances are not included as the main ion conductive material, organic solid electrolytes (polymer electrolytes such as polyethylene oxide (PEO), organic electrolytes such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), etc. It is clearly distinguished from electrolyte salt). Additionally, since the inorganic solid electrolyte is solid in a normal state, it usually does not dissociate or become liberated into cations and anions. In this respect, it is clearly distinguished from inorganic electrolyte salts (LiPF ₆ , LiBF ₄ , lithium bis(fluorosulfonyl)imide (LiFSI), LiCl, etc.) that are dissociated or liberated into cations and anions in the electrolyte solution or polymer. do. The inorganic solid electrolyte is not particularly limited as long as it has ion conductivity of a metal belonging to group 1 or 2 of the periodic table, and generally does not have electronic conductivity.

The inorganic solid electrolyte contained in the electrode composition of the present invention can be used by appropriately selecting solid electrolyte materials commonly used in all-solid-state secondary batteries. For example, the inorganic solid electrolyte includes (i) sulfide-based inorganic solid electrolyte, (ii) oxide-based inorganic solid electrolyte, (iii) halide-based inorganic solid electrolyte, and (iv) hydride-based inorganic solid electrolyte. From the viewpoint of being able to form a better interface between the active material and the inorganic solid electrolyte, a sulfide-based inorganic solid electrolyte is preferable.

When the all-solid-state secondary battery of the present invention is a lithium ion battery, the inorganic solid electrolyte preferably has ion conductivity of lithium ions.

(i) Sulfide-based inorganic solid electrolyte

The sulfide-based inorganic solid electrolyte preferably contains a sulfur atom, has ionic conductivity of a metal belonging to group 1 or 2 of the periodic table, and has electronic insulating properties. The sulfide-based inorganic solid electrolyte preferably contains at least Li, S, and P as elements and has lithium ion conductivity, but may also contain elements other than Li, S, and P as appropriate.

Examples of the sulfide-based inorganic solid electrolyte include a lithium-ion conductive inorganic solid electrolyte that satisfies the composition represented by the following formula (S1).

L _a1 M _b1 P _c1 S _d1 A _e1 (S1)

In formula (S1), L represents an element selected from Li, Na and K, and Li is preferable. M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge. A represents an element selected from I, Br, Cl, and F. a1~e1 represent the composition ratio of each element, and a1:b1:c1:d1:e1 satisfies 1~12:0~5:1:2~12:0~10. a1 is preferably 1 to 9, and more preferably 1.5 to 7.5. b1 is preferably 0 to 3, and more preferably 0 to 1. d1 is preferably 2.5 to 10, and more preferably 3.0 to 8.5. e1 is preferably 0 to 5, and more preferably 0 to 3.

The composition ratio of each element can be controlled by adjusting the blending amount of the raw material compound when producing the sulfide-based inorganic solid electrolyte as follows.

The sulfide-based inorganic solid electrolyte may be amorphous (glass) or crystallized (glass-ceramic), or only a portion may be crystallized. For example, Li-P-S-based glass containing Li, P, and S, or Li-P-S-based glass ceramics containing Li, P, and S can be used.

Sulfide-based inorganic solid electrolytes include, for example, lithium sulfide (Li ₂ S), phosphorus sulfide (e.g., diphosphorus pentasulfide (P ₂ S ₅ )), elemental phosphorus, elemental sulfur, sodium sulfide, and hydrogen sulfide. , lithium halide (e.g. LiI, LiBr, LiCl) and sulfide of the element represented by M (e.g. SiS ₂ , SnS, GeS ₂ ). It can be produced by reaction of at least two raw materials.

The ratio of Li ₂ S to P ₂ S ₅ in Li-PS-based glass and Li-PS-based glass ceramics is a molar ratio of Li ₂ S:P ₂ S ₅ , and is preferably 60:40 to 90:10. , more preferably 68:32 to 78:22. By keeping the ratio of Li ₂ S and P ₂ S ₅ within this range, lithium ion conductivity can be made high. Specifically, the lithium ion conductivity can be preferably 1×10 ^-4 S/cm or more, more preferably 1×10 ^-3 S/cm or more. There is no particular upper limit, but it is realistic to be 1×10 ^-1 S/cm or less.

As a specific example of a sulfide-based inorganic solid electrolyte, an example of a combination of raw materials is shown below. For example, Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -LiCl, Li ₂ SP ₂ S ₅ -H ₂ S, Li ₂ SP ₂ S ₅ -H ₂ S-LiCl, Li ₂ S-LiI- P ₂ S ₅ , Li ₂ S-LiI-Li ₂ OP ₂ S ₅ , Li ₂ S-LiBr-P ₂ S ₅ , Li ₂ S-Li ₂ OP ₂ S ₅ , Li ₂ S-Li ₃ PO ₄ -P ₂ S ₅ , Li ₂ SP ₂ S ₅ -P ₂ O ₅ , Li ₂ SP ₂ S ₅ -SiS ₂ , Li ₂ SP ₂ S ₅ -SiS ₂ -LiCl, Li ₂ SP ₂ S ₅ -SnS, Li ₂ SP ₂ S ₅ -Al ₂ S ₃ , Li ₂ S-GeS ₂ , Li ₂ S-GeS ₂ -ZnS, Li ₂ S-Ga ₂ S ₃ , Li ₂ S-GeS ₂ -Ga ₂ S ₃ , Li ₂ S- GeS ₂ -P ₂ S ₅ , Li ₂ S-GeS ₂ -Sb ₂ S ₅ , Li ₂ S-GeS ₂ -Al ₂ S ₃ , Li ₂ S-SiS ₂ , Li ₂ S-Al ₂ S ₃ , Li ₂ S-SiS ₂ -Al ₂ S ₃ , Li ₂ S-SiS ₂ -P ₂ S ₅ , Li ₂ S-SiS ₂ -P ₂ S ₅ -LiI, Li ₂ S-SiS ₂ -LiI, Li ₂ S-SiS ₂ -Li ₄ SiO ₄ , Li ₂ S-SiS ₂ -Li ₃ PO ₄ , Li ₁₀ GeP ₂ S ₁₂ and the like. However, the mixing ratio of each raw material does not matter. A method for synthesizing a sulfide-based inorganic solid electrolyte material using such a raw material composition includes, for example, an amorphization method. Examples of amorphization methods include mechanical milling, solution method, and melt quenching method. This is because processing at room temperature becomes possible and the manufacturing process can be simplified.

(ii) Oxide-based inorganic solid electrolyte

The oxide-based inorganic solid electrolyte preferably contains an oxygen atom, has ionic conductivity of a metal belonging to group 1 or 2 of the periodic table, and has electronic insulating properties.

The ionic conductivity of the oxide-based inorganic solid electrolyte is preferably 1×10 ^-6 S/cm or more, more preferably 5×10 ^-6 S/cm or more, and particularly preferably 1×10 ^-5 S/cm or more. do. The upper limit is not particularly limited, but is realistic to be 1×10 ^-1 S/cm or less.

Specific examples of compounds include, for example, Li _xa La _ya TiO ₃ [xa satisfies 0.3≤xa≤0.7, and ya satisfies 0.3≤ya≤0.7] (LLT); Li _xb La _yb Zr _zb M ^bb _mb O _nb (M ^bb is one or more elements selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In and Sn. ≤10, yb satisfies 1≤yb≤4, zb satisfies 1≤zb≤4, mb satisfies 0≤mb≤2, and nb satisfies 5≤nb≤20. ); Li _xc B _yc M ^cc _zc O _nc (M ^cc is one or more elements selected from C, S, Al, Si, Ga, Ge, In and Sn. satisfies 0<yc≤1, zc satisfies 0<zc≤1, and nc satisfies 0<nc≤6.); _{Li _ _ _ _ _} satisfies, ad satisfies 0≤ad≤1, md satisfies 1≤md≤7, and nd satisfies 3≤nd≤13.); ^Li _{( 3-2xe} ^{) M ee} indicates.); Li _xf Si _yf O _zf (xf satisfies 1≤xf≤5, yf satisfies 0<yf≤3, and zf satisfies 1≤zf≤10); Li _xg S _yg O _zg (xg satisfies 1≤xg≤3, yg satisfies 0<yg≤2, and zg satisfies 1≤zg≤10); Li ₃ BO ₃ ; Li ₃ BO ₃ -Li ₂ SO ₄ ; Li ₂ OB ₂ O ₃ -P ₂ O ₅ ; Li ₂ O-SiO ₂ ; Li ₆ BaLa ₂ Ta ₂ O ₁₂ ; Li ₃ PO _(4-3/2w) N _w (w is w<1); Li _3.5 Zn _0.25 GeO ₄ with LISICON (Lithium super ionic conductor) type crystal structure; La _0.55 Li _0.35 TiO ₃ with a perovskite-type crystal structure; LiTi ₂ P ₃ O ₁₂ with a NASICON (Natrium super ionic conductor) type crystal structure; Li _1+xh+yh (Al, Ga) _xh (Ti, Ge) _2-xh Si _yh P _3-yh O ₁₂ (xh satisfies 0≤xh≤1, yh satisfies 0≤yh≤1 .); Li ₇ La ₃ Zr ₂ O ₁₂ (LLZ), which has a garnet-type crystal structure, and the like.

Additionally, phosphorus compounds containing Li, P, and O are also preferred. For example lithium phosphate (Li ₃ PO ₄ ); LiPON, in which some of the oxygen elements of lithium phosphate are replaced with nitrogen elements; LiPOD ¹ (D ¹ is preferably one or more types selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt and Au) (It is an element.) etc. can be mentioned.

Additionally, LiA ¹ ON (A ¹ is one or more elements selected from Si, B, Ge, Al, C and Ga), etc. can also be preferably used.

(iii) Halide-based inorganic solid electrolyte

The halide-based inorganic solid electrolyte is preferably a compound that contains a halogen atom, has conductivity for ions of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulating properties.

The halide-based inorganic solid electrolyte is not particularly limited, but examples include LiCl, LiBr, LiI, and compounds such as Li ₃ YBr ₆ and Li ₃ YCl ₆ described in ADVANCED MATERIALS, 2018, 30, 1803075. . Among them, Li ₃ YBr ₆ and Li ₃ YCl ₆ are preferable.

(iv) hydride-based inorganic solid electrolyte

The hydride-based inorganic solid electrolyte is preferably a compound that contains a hydrogen atom, has ionic conductivity of a metal belonging to group 1 or 2 of the periodic table, and has electronic insulating properties.

The hydride-based inorganic solid electrolyte is not particularly limited, and examples include LiBH ₄ , Li ₄ (BH ₄ ) ₃ I, 3LiBH ₄ -LiCl, and the like.

The inorganic solid electrolyte contained in the electrode composition of the present invention is preferably in the form of particles in the electrode composition. The shape of the particles is not particularly limited and may be flat, amorphous, etc., but is preferably spherical or granular.

When the inorganic solid electrolyte is particulate, the particle diameter (volume average particle diameter) of the inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.1 μm or more, and more preferably 0.5 μm or more. The upper limit is preferably 100 μm or less, more preferably 50 μm or less, and more preferably 10 μm or less.

The particle diameter of the inorganic solid electrolyte is measured according to the following procedure. The inorganic solid electrolyte particles are diluted into a 1% by mass dispersion in a 20 mL sample bottle using water (heptane in the case of a water-unstable substance). The diluted dispersion sample is irradiated with 1 kHz ultrasound for 10 minutes and used for testing immediately thereafter. Using this dispersion sample, data was entered 50 times using a laser diffraction/scattering type particle size distribution measuring device LA-920 (product name, manufactured by HORIBA) at a temperature of 25°C using a quartz cell for measurement, and the volume average particle diameter was determined. get For other detailed conditions, etc., refer to the description of Japanese Industrial Standards (JIS) Z 8828:2013 "Particle diameter analysis - dynamic light scattering method" as necessary. Five samples are produced per level and the average value is adopted.

The method of adjusting the particle size is not particularly limited, and known methods can be applied, for example, a method using a normal grinder or classifier. As a crusher or classifier, for example, a mortar, ball mill, sand mill, vibrating ball mill, satellite ball mill, planetary ball mill, swirling jet mill or sieve, etc. are suitably used. During pulverization, wet pulverization can be performed in which a dispersion medium such as water or methanol coexists. In order to achieve the desired particle size, it is desirable to perform classification. Classification is not particularly limited and can be performed using a sieve, wind classifier, etc. Classification can be done in both dry and wet ways.

The number of inorganic solid electrolytes contained in the electrode composition may be one, or two or more types may be used.

The content of the inorganic solid electrolyte (SE) in the electrode composition is not particularly limited and is determined appropriately. For example, in terms of dispersion characteristics and binding properties, the total solid content of 100% by mass of the active material (AC) is preferably 50% by mass or more, more preferably 70% by mass or more, and especially 90% by mass or more. desirable. From the same viewpoint, the upper limit is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and especially preferably 99% by mass or less.

In the present invention, solid content (solid component) refers to a component that does not volatilize or evaporate and disappear when the electrode composition is dried at 150°C for 6 hours in a nitrogen atmosphere under an atmospheric pressure of 1 mmHg. Typically, components other than the dispersion medium (D) described later are indicated. In addition, the content in total solid content refers to the content in 100% by mass of the total mass of solid content.

In 100% by mass of solid content of the electrode composition, the ratio of the content of the inorganic solid electrolyte (SE) and the content of the active material described later [content of the inorganic solid electrolyte (SE):content of the active material] is not particularly limited, but is, for example, For example, it is preferable that it is 1:1 to 1:6, and it is more preferable that it is 1:1.2 to 1:5.

<Active material (AC)>

The electrode composition of the present invention contains an active material (AC) capable of inserting and releasing metal ions belonging to group 1 or 2 of the periodic table.

Examples of the active material (AC) include a positive electrode active material and a negative electrode active material, as explained below.

(positive electrode active material)

The positive electrode active material is an active material capable of inserting and releasing metal ions belonging to group 1 or 2 of the periodic table, and is preferably capable of reversibly inserting and releasing lithium ions. The material is not particularly limited as long as it has the above-mentioned properties, and may be an element that decomposes the battery and complexes with Li, such as a transition metal oxide or sulfur.

Among them, as the positive electrode active material, it is preferable to use a transition metal oxide, and a transition metal oxide having a transition metal element M ^a (one or more elements selected from Co, Ni, Fe, Mn, Cu, and V) is more preferable. In addition, this transition metal oxide contains elements M ^b (elements of group 1 (Ia), elements of group 2 (IIa) of the periodic table of metals other than lithium, Al, Ga, In, Ge, Sn, Pb, Sb, Bi , elements such as Si, P and B) may be mixed. The mixing amount is preferably 0 to 30 mol% relative to the amount (100 mol%) of the transition metal element M ^a . Those synthesized by mixing so that the molar ratio of Li/M ^a is 0.3 to 2.2 are more preferable.

Specific examples of transition metal oxides include (MA) a transition metal oxide having a layered halite-type structure, (MB) a transition metal oxide having a spinel-type structure, (MC) a lithium-containing transition metal phosphate compound, and (MD) a lithium-containing transition metal oxide. Rosenated phosphoric acid compounds and (ME) lithium-containing transition metal silicic acid compounds can be mentioned.

(MA) Specific examples of transition metal oxides having a layered rock salt-type structure include LiCoO ₂ (lithium cobaltate [LCO]), LiNi ₂ O ₂ (lithium nickelate), LiNi _0.85 Co _0.10 Al _0.05 O ₂ (nickel cobalt aluminum) Lithium acid [NCA]), LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (lithium nickel manganese cobaltate [NMC]), and LiNi _0.5 Mn _0.5 O ₂ (lithium manganese nickelate). .

(MB) Specific examples of transition metal oxides having a spinel-type structure include LiMn ₂ O ₄ (LMO), LiCoMnO ₄ , Li ₂ FeMn ₃ O ₈ , Li ₂ CuMn ₃ O ₈ , Li ₂ CrMn ₃ O ₈ and Li ₂ NiMn ₃ O ₈ may be mentioned.

(MC) Examples of lithium-containing transition metal phosphate compounds include olivine-type iron phosphates such as LiFePO ₄ and Li ₃ Fe ₂ (PO ₄ ) ₃ , iron pyrophosphates such as LiFeP ₂ O ₇ , and phosphoric acids such as LiCoPO ₄ Examples include monoclinic nasicon type vanadium phosphate salts such as cobalt and Li ₃ V ₂ (PO ₄ ) ₃ (lithium vanadium phosphate).

(MD) Examples of lithium-containing transition metal halide phosphoric acid compounds include iron fluorophosphoric acid salts such as Li ₂ FePO ₄ F, manganese fluorophosphoric acid salts such as Li ₂ MnPO ₄ F, and fluorinated phosphoric acid salts such as Li ₂ CoPO ₄ F. Examples include cobalt phosphate.

(ME) Examples of the lithium-containing transition metal silicic acid compound include Li ₂ FeSiO ₄ , Li ₂ MnSiO ₄ , and Li ₂ CoSiO ₄ .

In the present invention, a transition metal oxide having a (MA) layered rock salt type structure is preferred, and LCO or NMC is more preferred.

The positive electrode active material contained in the electrode composition of the present invention is preferably in particulate form in the electrode composition. The shape of the particles is not particularly limited and may be flat, amorphous, etc., but is preferably spherical or granular.

When the positive electrode active material is in particulate form, the particle diameter (volume average particle diameter) of the positive electrode active material is not particularly limited, but for example, 0.1 to 50 μm is preferable, and 0.5 to 10 μm is more preferable. The particle diameter of the positive electrode active material particles can be adjusted to be the same as that of the inorganic solid electrolyte, and the measurement method can also be measured in the same manner as that of the inorganic solid electrolyte.

The positive electrode active material obtained by the firing method may be used after washing with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

The number of positive electrode active materials contained in the electrode composition of the present invention may be one, or two or more types may be used.

The content of the positive electrode active material in the electrode composition is not particularly limited and is determined appropriately. For example, in 100 mass% of solid content, 10 to 97 mass% is preferable, 30 to 95 mass% is more preferable, 40 to 93 mass% is more preferable, and 50 to 90 mass% is especially preferable.

(Negative active material)

The negative electrode active material is an active material capable of inserting and releasing metal ions belonging to group 1 or 2 of the periodic table, and is preferably capable of reversibly inserting and releasing lithium ions. The material is not particularly limited as long as it has the above-mentioned properties, and examples include carbonaceous materials, metal oxides, metal composite oxides, lithium alone, lithium alloys, and negative electrode active materials capable of forming an alloy with lithium (alloying is possible). Among them, carbonaceous materials, metal composite oxides, or lithium alone are preferably used from the viewpoint of reliability. In order to enable increased capacity of all-solid-state secondary batteries, an active material that can be alloyed with lithium is preferable.

The carbonaceous material used as the negative electrode active material is a material substantially made of carbon. For example, carbon black such as petroleum pitch and acetylene black (AB), graphite (natural graphite, artificial graphite such as vapor-grown graphite, etc.), and PAN (polyacrylonitrile)-based resin or fur. Carbonaceous materials obtained by baking various synthetic resins such as furyl alcohol resin can be mentioned. In addition, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA (polyvinyl alcohol)-based carbon fiber, lignin carbon fiber, glassy carbon fiber, and activated carbon fiber; Mesophase microspheres, graphite whiskers, and flat graphite may also be mentioned.

These carbonaceous materials can be divided into non-graphitizable carbonaceous materials (also called hard carbon) and graphite-based carbonaceous materials depending on the degree of graphitization. Additionally, the carbonaceous material preferably has the interplanar spacing, density, and crystallite size described in Japanese Patent Application Laid-Open Nos. 62-22066, 2-6856, and 3-45473. The carbonaceous material does not need to be a single material, and a mixture of natural graphite and artificial graphite described in Japanese Patent Application Laid-Open No. 5-90844, graphite with a coating layer described in Japanese Patent Application Laid-Open No. 6-4516, etc. may be used. .

As a carbonaceous material, hard carbon or graphite is preferably used, and graphite is more preferably used.

The oxide of a metal or semi-metal element applied as a negative electrode active material is not particularly limited as long as it is an oxide that can occlude and release lithium, and may include an oxide of a metal element (metal oxide), a composite oxide of a metal element, or a composite of a metal element and a semi-metal element. Examples include oxides (collectively referred to as metal composite oxides) and oxides of semimetal elements (semimetal oxides). As these oxides, amorphous oxides are preferable, and chalcogenides, which are reaction products of metal elements and elements of group 16 of the periodic table, are also preferable. In the present invention, a semimetal element refers to an element that exhibits properties intermediate between a metal element and a non-metallic element, and usually includes six elements: boron, silicon, germanium, arsenic, antimony, and tellurium, and further includes Contains the three elements of selenium, polonium and astatine. In addition, amorphous means having a wide scattering band with a vertex in the range of 20° to 40° at 2θ value by X-ray diffraction method using CuKα rays, and may have crystalline diffraction lines. It is preferable that the strongest intensity of the crystalline diffraction lines visible between 40° and 70° in 2θ values is 100 times or less, and 5 times or less, of the diffraction line intensity at the vertex of the wide scattering band visible between 20° and 40° in 2θ values. It is more preferable, and it is especially preferable that it does not have a crystalline diffraction line.

Among the compound group consisting of the amorphous oxide and chalcogenide, the amorphous oxide of a semimetal element or the chalcogenide is more preferable, and elements of groups 13 (IIIB) to 15 (VB) of the periodic table (for example, Al , Ga, Si, Sn, Ge, Pb, Sb and Bi) or a (composite) oxide or chalcogenide consisting of one type selected from the group consisting of (a) one type alone or a combination of two or more types thereof, or a chalcogenide. Specific examples of preferred amorphous oxides and chalcogenides include Ga ₂ O ₃ , GeO, PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₈ Bi ₂ O ₃ , Sb ₂ O ₈ Si ₂ O ₃ , Sb ₂ O ₅ , Bi ₂ O ₃ , Bi ₂ O ₄ , GeS, PbS, PbS ₂ , Sb ₂ S ₃ or Sb ₂ S Preferred examples include ₅ .

Negative electrode active materials that can be used together with amorphous oxides centered on Sn, Si, and Ge include carbonaceous materials that can occlude and/or release lithium ions or lithium metal, lithium alone, lithium alloys, and negative electrode active materials that can be alloyed with lithium. can be suitably mentioned.

It is preferable that oxides of metal or semimetal elements, especially metal (composite) oxides, and the above-mentioned chalcogenides contain at least one of titanium and lithium as a constituent from the viewpoint of high current density charge and discharge characteristics. Examples of metal complex oxides containing lithium (lithium complex metal oxide) include complex oxides of lithium oxide and the metal (composite) oxide or the above chalcogenide, more specifically, Li ₂ SnO ₂ . .

The negative electrode active material, for example, a metal oxide, preferably contains titanium element (titanium oxide). Specifically, Li ₄ Ti ₅ O ₁₂ (lithium titanate [LTO]) has excellent rapid charging and discharging characteristics in that the volume fluctuation during insertion and release of lithium ions is small, and deterioration of the electrode is suppressed, making it suitable for lithium ion secondary batteries. This is desirable because it allows for improved lifespan.

The lithium alloy as the negative electrode active material is not particularly limited as long as it is an alloy commonly used as the negative electrode active material for secondary batteries. For example, lithium aluminum alloy, specifically, lithium aluminum with lithium as the base metal and 10% by mass of aluminum added. alloys may be mentioned.

The negative electrode active material capable of forming an alloy with lithium is not particularly limited as long as it is commonly used as a negative electrode active material for secondary batteries. Such active materials have large expansion and contraction due to charging and discharging of all-solid-state secondary batteries, and accelerate the decline in cycling characteristics. However, since the electrode composition of the present invention contains polymer binders A and B, which will be described later, the decline in cycling characteristics is reduced. It can be suppressed. Examples of such active materials include (negative electrode) active materials (alloys, etc.) containing a silicon element or a tin element, and various metals such as Al and In, and negative electrode active materials (silicon elements) containing a silicon element that enable higher battery capacity. active material containing the silicon element) is preferable, and an active material containing the silicon element having a content of the silicon element of 50 mol% or more of the total constituent elements is more preferable.

In general, negative electrodes containing these negative electrode active materials (e.g., Si negative electrodes containing active materials containing a silicon element, Sn negative electrodes containing an active material containing a tin element, etc.) are compared to carbon negative electrodes (such as graphite and acetylene black). , more Li ions can be stored. That is, the storage amount of Li ions per unit mass increases. Therefore, the battery capacity (energy density) can be increased. As a result, there is an advantage in that the battery operation time can be extended.

Active materials containing silicon elements include, for example, silicon materials such as Si, _SiO alloys (for example, LaSi ₂ , VSi ₂ , La-Si, Gd-Si, Ni-Si), or structured active materials (for example, LaSi ₂ /Si), as well as SnSiO ₃ and SnSiS ₃ Active materials containing silicon element and tin element, etc. can be mentioned. In addition, _SiO You can.

Examples of the negative electrode active material containing the tin element include Sn, SnO, SnO ₂ , SnS, SnS ₂ , and further active materials containing the above-mentioned silicon element and tin element. Additionally, a complex oxide with lithium oxide, for example, Li ₂ SnO ₂ , can also be used.

In the present invention, the above-described negative electrode active material can be used without particular restrictions, but from the viewpoint of battery capacity, a negative electrode active material capable of alloying with lithium is a preferable embodiment, and among these, the silicon material or silicon-containing alloy (silicon an alloy containing the element) is more preferred, and one containing silicon (Si) or a silicon-containing alloy is more preferred.

The negative electrode active material contained in the electrode composition of the present invention is preferably in the form of particles in the electrode composition. The shape of the particles is not particularly limited and may be flat, amorphous, etc., but is preferably spherical or granular.

When the negative electrode active material is in particulate form, the particle diameter (volume average particle diameter) of the negative electrode active material is not particularly limited, but is preferably 0.1 to 60 μm, and more preferably 0.5 to 10 μm. The particle size of the negative electrode active material particles can be adjusted to be the same as that of the inorganic solid electrolyte, and the measurement method can also be measured using the same method as that of the inorganic solid electrolyte.

The number of negative electrode active materials contained in the electrode composition of the present invention may be one, or two or more types may be used.

The content of the negative electrode active material in the electrode composition is not particularly limited and is determined appropriately. For example, with respect to 100 mass% of solid content, it is preferably 10 to 90 mass%, more preferably 20 to 85 mass%, more preferably 30 to 80 mass%, and even more preferably 40 to 75 mass%. desirable.

In the present invention, the negative electrode active material layer can also be formed by charging the secondary battery. In this case, instead of the negative electrode active material, ions of a metal belonging to group 1 or 2 of the periodic table occurring in an all-solid-state secondary battery can be used. By combining these ions with electrons and precipitating them as metal, a negative electrode active material layer can be formed.

The chemical formula of the compound obtained by the above-mentioned calcination method can be calculated by inductively coupled plasma (ICP) emission spectroscopy as a measurement method and from the mass difference of the powder before and after calcination as a simple method.

(Coating of active material)

The surfaces of the positive electrode active material and the negative electrode active material may be coated with another metal oxide. Examples of surface coating agents include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. Specifically, titanium acid spinel, tantalum-based oxide, niobium-based oxide, lithium niobate-based compound, etc. are mentioned. Specifically, Li ₄ Ti ₅ O ₁₂ , Li ₂ Ti ₂ O ₅ , LiTaO ₃ , LiNbO ₃ , LiAlO ₂ , Li ₂ ZrO ₃ , Li ₂ WO ₄ , Li ₂ TiO ₃ , Li ₂ B ₄ O ₇ , Li ₃ PO ₄ , Li ₂ MoO ₄ , Li ₃ BO ₃ , LiBO ₂ , Li ₂ CO ₃ , Li ₂ SiO ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , Al ₂ O ₃ , B ₂ O ₃ , etc.

Additionally, the electrode surface containing the positive electrode active material or the negative electrode active material may be surface treated with sulfur or phosphorus.

In addition, the surface of the particles of the positive electrode active material or the negative electrode active material may be subjected to surface treatment using actinic rays or active gas (plasma, etc.) before and after the surface coating.

<Polymer binder (PB)>

The polymer binder (PB) contained in the electrode composition of the present invention contains one or two or more types of polymer binder A below, and also contains one type or two or more types of polymer binder B below.

Polymer binder A: dissolved in the dispersion medium (D), the adsorption rate to the active material (AC) in the dispersion medium (D) is 20% or more, and is greater than the adsorption rate to the inorganic solid electrolyte (SE) (hereinafter, polymer Binder A is sometimes called an AC adsorption binder.)

Polymer binder B: dissolved in the dispersion medium (D), the adsorption rate to the inorganic solid electrolyte (SE) in the dispersion medium (D) is 20% or more, and is greater than the adsorption rate to the active material (AC) (hereinafter, polymer Binder B is sometimes called a SE adsorption binder.)

(polymer binder A)

The polymer binder A exhibits the property of dissolving (solubility) in the dispersion medium (D) contained in the electrode composition. A polymer binder that dissolves in a dispersion medium is called a soluble binder. The polymer binder A in the electrode composition varies depending on its content, solubility described later, content of the dispersion medium (D), etc., but usually exists in a state dissolved in the dispersion medium (D) in the electrode composition. As a result, the polymer binder A stably exerts the function of dispersing the active material (AC) in the dispersion medium (D).

In the present invention, the fact that the polymer binder (PB) is dissolved in the dispersion medium (D) means that the solubility in the dispersion medium (D) in the solubility measurement is 10% by mass or more. On the other hand, the fact that the polymer binder is not soluble (insoluble) in the dispersion medium means that the solubility in the dispersion medium (D) in the solubility measurement is less than 10% by mass. The method of measuring solubility is as follows.

A specified amount of the polymer binder (PB) to be measured is weighed in a glass bottle, 100 g of the same dispersion medium (D) as the dispersion medium (D) contained in the electrode composition is added thereto, and placed on a mix rotor at a temperature of 25°C. and stirred for 24 hours at a rotation speed of 80 rpm. The transmittance of the mixed solution obtained in this way after stirring for 24 hours was measured under the following conditions. For this test (transmittance measurement), the dissolution amount (specified above) of the polymer binder (PB) was changed and the upper limit concentration It is based on solubility.

<Transmittance measurement conditions>

Dynamic light scattering (DLS) measurements

Device: Otsuka Electronics DLS measuring device DLS-8000

Laser wavelength, power: 488nm/100mW

Sample cell: NMR tube

The polymer binder A has an adsorption rate A _AC of 20% or more to the active material (AC) in the dispersion medium (D), and is also greater than the adsorption rate A _SE to the inorganic solid electrolyte (SE). As a result, the polymer binder A is preferentially adsorbed to the active material (AC) rather than the inorganic solid electrolyte (SE), and the dispersion characteristics and binding properties of the active material (AC) can be improved, and its content can also be reduced.

The adsorption rate A _AC of the polymer binder A may be 20% or more, and from the viewpoint of polymer binder content, dispersion stability and binding properties, it is preferably 30% or more, more preferably 40% or more, and even more preferably 60% or more. do. The upper limit of the adsorption rate A _AC is not particularly limited, but usually, as the adsorption rate A _AC increases, the adsorption rate A _SE also increases accordingly, which may inhibit preferential adsorption to the active material (AC). Therefore, the upper limit can be, for example, 95% or less, but is preferably 90% or less, more preferably 80% or less, and can also be 60%.

The adsorption rate A _SE of the polymer binder A is not particularly limited as long as it is smaller than the above-mentioned adsorption rate A _AC , and is appropriately determined depending on the value of the adsorption rate A _AC . The adsorption rate A _SE is, for example, preferably 45% or less, more preferably 35% or less, more preferably 20% or less, particularly preferably 15% or less, and most preferably 10% or less.

In the polymer binder A, the difference (A _AC -A _SE ) between the adsorption rate A _AC and the adsorption rate A _SE is not particularly limited, and is preferably greater than 0%, more preferably 5% or more, and 10%. It is more desirable to have more than that. The upper limit is not particularly limited, but can be, for example, 30%.

In the present invention, the adsorption rate (%) of the polymer binder (PB), that is, polymer binder A or B, is determined by using the active material (AC) or inorganic solid electrolyte (SE) contained in the electrode composition, and a specific dispersion medium (D). This is a measured value, and is an indicator of the degree to which the polymer binder (PB) is adsorbed to the active material (AC) or inorganic solid electrolyte (SE) in the dispersion medium (D). Here, the adsorption of the polymer binder (PB) to the active material (AC) or inorganic solid electrolyte (SE) includes not only physical adsorption but also chemical adsorption, as described above.

When the electrode composition contains multiple types of active material (AC) or inorganic solid electrolyte (SE), the active material (AC) or inorganic solid electrolyte (SE) has the same composition as the active material composition or inorganic solid electrolyte composition (type and content) in the electrode composition SE) is taken as the adsorption rate. Similarly, when the electrode composition contains multiple types of specific dispersion media (D), the adsorption rate is measured using the dispersion medium (D) having the same composition as the specific dispersion medium (type and content) in the electrode composition.

When the electrode composition contains multiple types of polymer binders A or B, the adsorption rate is measured for each polymer binder.

The adsorption rate A _AC (%) of the polymer binder (PB) to the active material (AC) is as follows using the active material (AC), polymer binder (PB), and dispersion medium (D) used in the preparation of the electrode composition. and measure.

That is, 1.6 g of the active material (AC) and 0.08 g of the polymer binder (PB) were placed in a 15 mL vial, and while stirring with a mix rotor, 8 g of the dispersion medium (D) was added, and the mixture was stirred at room temperature (25°C) for 30 minutes at 80 rpm. Stir further. The dispersion after stirring was filtered through a filter with a pore diameter of 1 μm, and 2 g of the total 8 g of the filtrate was collected and dried, and the mass of the dry polymer binder (PB) (the mass of the polymer binder (PB) that was not adsorbed to the active material (AC) was calculated. ) Measure BY.

From the mass BY of the polymer binder (PB) obtained in this way and the mass of 0.08 g of the polymer binder (PB) used, the adsorption rate A _AC (%) of the polymer binder (PB) to the active material (AC) was calculated by the following formula: Calculate The average value of the adsorption rate (%) obtained by performing this measurement twice is taken as the adsorption rate A _AC (%) of the polymer binder (PB).

Adsorption rate A _AC (%)=[(0.08-BY×8/2)/0.08]×100

The adsorption rate A _SE (%) of the polymer binder (PB) to the inorganic solid electrolyte (SE) is determined by using the inorganic solid electrolyte (SE), polymer binder (PB), and dispersion medium (D) used in the preparation of the electrode composition. , Measure as follows.

That is, 0.5 g of inorganic solid electrolyte (SE) and 0.26 g of polymer binder (PB) were placed in a 15 mL vial, and while stirring with a mix rotor, 25 g of dispersion medium (D) was added, and stirred at room temperature and 80 rpm for an additional 30 minutes. . The stirred dispersion was filtered through a filter with a pore diameter of 1 μm, and 2 g of the total 25 g of the filtrate was collected, dried, and the mass of the dry polymer binder (PB) (polymer binder (PB) that was not adsorbed to the inorganic solid electrolyte (SE) was obtained. mass) Measure BX.

From the mass BX of the polymer binder (PB) obtained in this way and the mass of 0.26 g of the polymer binder (PB) used, the adsorption rate A _SE (% ) is calculated. The average value of the adsorption rate (%) obtained by performing this measurement twice is taken as the adsorption rate A _SE (%) of the polymer binder (PB).

Adsorption rate A _SE (%)=[(0.26-BX×25/2)/0.26]×100

In the present invention, the positive adsorption rate of the polymer binder A can be appropriately set depending on the type of polymer forming the polymer binder A (structure and composition of the polymer chain), the type or content of the functional group the polymer has, etc.

In addition, other characteristics of polymer binder A will be described later.

(polymer binder B)

The polymer binder B exhibits the property of being soluble in the dispersion medium (D) contained in the electrode composition. The polymer binder B in the electrode composition varies depending on its content, solubility described later, content of the dispersion medium (D), etc., but usually exists in a state dissolved in the dispersion medium (D) in the electrode composition. As a result, the polymer binder B stably exerts the function of dispersing the inorganic solid electrolyte (SE) in the dispersion medium (D).

The polymer binder B has an adsorption rate A _SE of 20% or more to the inorganic solid electrolyte (SE) in the dispersion medium (D), and is also greater than the adsorption rate A _AC to the active material (AC). As a result, the polymer binder B is preferentially adsorbed to the inorganic solid electrolyte (SE) rather than the active material (AC), the dispersion characteristics and binding properties of the inorganic solid electrolyte (SE) can be improved, and its content can also be reduced.

The adsorption rate A _SE of the polymer binder B may be 20% or more, and from the viewpoint of the polymer binder content, dispersion stability and binding properties, it is preferably 30% or more, more preferably 40% or more, and still more preferably 60% or more. do. The upper limit of the adsorption rate A _SE is not particularly limited, but usually, as the adsorption rate A _SE increases, the adsorption rate A _AC also increases accordingly, which may inhibit preferential adsorption to the inorganic solid electrolyte (SE). Therefore, the upper limit can be, for example, 95% or less, preferably 90% or less, more preferably 80% or less, and can also be 60%.

The adsorption rate A _AC of the polymer binder B is not particularly limited as long as it is smaller than the above-mentioned adsorption rate A _SE , and is appropriately determined depending on the value of the adsorption rate A _SE . The adsorption rate A _AC is, for example, preferably 35% or less, more preferably 20% or less, further preferably 15% or less, and especially preferably 10% or less.

In the polymer binder B, the difference between the adsorption rate A _SE and the adsorption rate A _AC (A _SE -A _AC ) is not particularly limited, and is preferably greater than 0%, more preferably 5% or more, and 10%. It is more desirable to have more than that. The upper limit is not particularly limited, but can be, for example, 35%.

The adsorption rates A _SE and A _AC of polymer binder B are taken as the values calculated by the measurement method described above.

In the combination of polymer binder A and polymer binder B, the difference in adsorption rate A _SE or A _AC is not particularly limited, but since more selective adsorption to the active material (AC) is possible, polymer binder A and polymer binder The difference (absolute value) between the adsorption rate A _AC of B is preferably 5% or more, more preferably 10% or more, more preferably 15% or more, and still more preferably 30% or more. Likewise, in order to enable highly selective adsorption to the inorganic solid electrolyte (SE), the difference (absolute value) in the adsorption rate A _SE between polymer binder A and polymer binder B is preferably 5% or more, and is preferably 10%. It is more preferable that it is more than 15%, and it is more preferable that it is more than 15%. The upper limits of the difference (absolute value) of the adsorption rate A _AC and the difference (absolute value) of the adsorption rate A _SE are not particularly limited and can be determined appropriately. For example, the difference (absolute value) in the adsorption rate A _AC is preferably 60% or less, and more preferably 50% or less. On the other hand, the difference (absolute value) in the adsorption rate A _SE is preferably 30% or less, more preferably 20% or less, and can also be 10% or less.

In the present invention, the positive adsorption rate of polymer binder B can be appropriately set depending on the type of polymer forming polymer binder B (structure and composition of the polymer chain), the type or content of the functional group the polymer has, etc.

In addition, other characteristics of polymer binder B will be described later.

-Polymers forming polymer binders A and B-

The polymer forming polymer binder A or B, respectively, provides solubility to the polymer binder in the dispersion medium (D) and satisfies the above adsorption rate to the active material (AC) or inorganic solid electrolyte (SE). As long as there is no particular limitation, various polymers can be used. Among them, a polymer having a polymer chain of at least one bond selected from a urethane bond, a urea bond, an amide bond, an imide bond, and an ester bond, or a carbon-carbon double bond in the main chain is preferably mentioned. In the present invention, the polymer chain of a carbon-carbon double bond refers to a polymer chain formed by polymerization of a carbon-carbon double bond (ethylenically unsaturated group), and specifically, the polymerization chain of a monomer having a carbon-carbon unsaturated bond. It refers to a polymer chain formed by (homopolymerization or copolymerization).

In the present invention, the main chain of a polymer refers to a linear molecular chain in which all other molecular chains constituting the polymer can be regarded as branch chains or pendant groups with respect to the main chain. It also varies depending on the mass average molecular weight of the molecular chain, which is considered a branched chain or a pendant chain, but typically, the longest chain among the molecular chains constituting the polymer is the main chain. However, the terminal group of the polymer terminal is not included in the main chain. In addition, the side chain of a polymer refers to a molecular chain other than the main chain and includes short molecular chains and long molecular chains.

The bond is not particularly limited as long as it is included in the main chain of the polymer, and may be included in a structural unit (repeating unit) and/or as a bond connecting different structural units. Moreover, the said bond contained in a main chain is not limited to 1 type, 2 or more types may be sufficient, 1-6 types are preferable, and 1-4 types are more preferable. In this case, the bonding pattern of the main chain is not particularly limited, and may have two or more types of bonds randomly, or may be a segmented main chain of a segment having a specific bond and a segment having a different bond.

The main chain having the above bonds is not particularly limited, but a main chain having at least one segment of the above bonds is preferable, and a main chain made of polyamide, polyurea, polyurethane, or (meth)acrylic polymer is more preferable, A main chain made of polyurethane or (meth)acrylic polymer is more preferable.

Among the above bonds, polymers having a urethane bond, a urea bond, an amide bond, an imide bond, or an ester bond in the main chain include, for example, polyurethane, polyurea, polyamide, polyimide, and polyester. Polymerization (polycondensation, polyaddition or addition condensation) polymers or copolymers thereof can be mentioned. The copolymer may be a block copolymer in which each polymer is segmented, or a random copolymer in which components of two or more of the polymers are randomly combined.

Polymers having a polymer chain of carbon-carbon double bonds in the main chain, that is, polymers having a polymer chain in the main chain formed by polymerizing monomers having carbon-carbon unsaturated bonds, include fluoropolymers (fluorinated polymers), hydrocarbon polymers, and vinyl polymers. , chain polymerization polymers such as (meth)acrylic polymer. The polymerization mode of these chain polymerization polymers is not particularly limited, and may be any of block copolymers, alternating copolymers, and random copolymers.

The number of polymers forming the binder may be one, or two or more types may be used.

The polymer forming the binder preferably has a component represented by any of the following formulas (1-1) to (1-5), and is represented by the following formula (1-1) or (1-2) It is more preferable to have a component.

[Formula 1]

In formula (1-1), R ¹ represents a hydrogen atom or an alkyl group (the number of carbon atoms is preferably 1 to 12, more preferably 1 to 6, and still more preferably 1 to 3). The alkyl group that can be employed as R ¹ may have a substituent. The substituent is not particularly limited, but includes the substituent Z described later, and groups other than the functional group selected from the functional group group (a) are preferable, and suitable examples include a halogen atom.

R ² represents a group having a hydrocarbon group having 4 or more carbon atoms. In the present invention, the group having a hydrocarbon group is a group consisting of the hydrocarbon group itself (the hydrocarbon group is directly bonded to the carbon atom in the formula above to which R ¹ is bonded) and the carbon atom in the formula above to which R ² is bonded. Includes a group consisting of a linking group connecting an atom and a hydrocarbon group (the hydrocarbon group is bonded to the carbon atom in the above formula to which R ¹ is bonded through a linking group).

A hydrocarbon group is a group composed of a carbon atom and a hydrogen atom, and is usually introduced into the end of R ² . The hydrocarbon group is not particularly limited, but an aliphatic hydrocarbon group is preferable, an aliphatic saturated hydrocarbon group (alkyl group) is more preferable, and a straight-chain or branched alkyl group is more preferable. The number of carbon atoms of the hydrocarbon group may be 4 or more, preferably 6 or more, more preferably 8 or more, and may be 10 or more. The upper limit is not particularly limited, and is preferably 20 or less, and more preferably 14 or less.

The linking group is not particularly limited, but examples include an alkylene group (carbon number is preferably 1 to 12, more preferably 1 to 6, more preferably 1 to 3), alkenylene group (carbon number is 2 to 3) 6 is preferable, 2 to 3 is more preferable), arylene group (carbon number is preferably 6 to 24, and 6 to 10 are more preferable), oxygen atom, sulfur atom, imino group (-NR ^N -: R ^N represents a hydrogen atom, an alkyl group with 1 to 6 carbon atoms, or an aryl group with 6 to 10 carbon atoms.), a carbonyl group, a phosphoric acid linking group (-OP(OH)(O)-O-), a phosphonic acid linking group (-P(OH) )(O)-O-), or a combination thereof. A polyalkyleneoxy chain can also be formed by combining an alkylene group and an oxygen atom. As the linking group, a group formed by combining an alkylene group, an arylene group, a carbonyl group, an oxygen atom, a sulfur atom, and an imino group is preferable, and a group formed by combining an alkylene group, an arylene group, a carbonyl group, an oxygen atom, and an imino group is more preferable. , -CO-O-group, -CO-N(R ^N )-group (R ^N is as described above) is more preferable, and -CO-O-group or -CO-N(R ^N )-group (R ^N is as described above) is particularly preferred. The number of atoms constituting the linking group and the number of linking atoms are as described later. However, the polyalkyleneoxy chain constituting the linking group is not limited to the above.

In the present invention, the number of atoms constituting the linking group is preferably 1 to 36, more preferably 1 to 24, more preferably 1 to 12, and especially preferably 1 to 6. The number of connected atoms of the linking group is preferably 10 or less, and more preferably 8 or less. As a lower limit, it is 1 or more. The number of connecting atoms refers to the minimum number of atoms connecting certain structural parts. For example, in the case of -CH ₂ -C(=O)-O-, the number of atoms constituting the linking group is 6, but the number of linking atoms is 3.

The hydrocarbon group and the linking group may or may not each have a substituent. Examples of the substituent that may be included include the substituent Z. Groups other than the functional group selected from the functional group group (a) are preferable, and suitable examples include a halogen atom.

In the above formula (1-1), the carbon atom adjacent to the carbon atom to which R ¹ is bonded has two hydrogen atoms, but may have one or two substituents in the present invention. This substituent is not particularly limited, but includes the substituent Z described later, and groups other than the functional group selected from the functional group group (a) are preferable.

The compound that derives the component represented by formula (1-1) is not particularly limited, but examples include (meth)acrylic acid straight-chain alkyl ester compounds (linear-chain alkyl refers to an alkyl group having 4 or more carbon atoms).

In Formulas (1-2) to (1-5), R ³ is the mass average molecular weight or number average molecular weight (hereinafter referred to as mass average molecular weight, etc.) containing a polybutadiene chain or a polyisoprene chain. ) represents a linking group of 500 to 200,000.

The terminal of the chain that can be used as R ³ can be appropriately changed to a normal chemical structure that can be introduced as R ³ into the constituents represented by each of the above formulas.

In each of the above formulas, R ³ is a divalent molecular chain, but at least one hydrogen atom is replaced with -NH-CO-, -CO-, -O-, -NH-, or -N<, so that the chain is trivalent or higher. It can be done.

The polybutadiene chain and polyisoprene chain that can be used as R ³ include known chains made of polybutadiene and polyisoprene, respectively, as long as they satisfy the mass average molecular weight, etc. The polybutadiene chain and the polyisoprene chain are both diene polymers having a double bond in the main chain, but in the present invention, they are polymers in which the double bond is hydrogenated (reduced) (for example, a double bond is added to the main chain). non-diene polymers). In the present invention, hydrides of polybutadiene chains or polyisoprene chains are preferred.

As raw material compounds, the polybutadiene chain and the polyisoprene chain preferably have a reactive group at the terminal, and more preferably have a polymerizable terminal reactive group. The polymerizable terminal reactive group polymerizes to form a group that binds to R ³ in each of the above formulas. Examples of such terminal reactive groups include hydroxy groups, carboxy groups, and amino groups, and among them, hydroxy groups are preferable. Examples of polybutadiene and polyisoprene having a terminal reactive group are all brand names, including NISSO-PB series (manufactured by Nippon Soda Corporation), Claysol series (manufactured by Tomoe Kogyo Corporation), and PolyVEST-HT series (manufactured by Evonik Corporation). , poly-bd series (manufactured by Idemitsu Kosan Corporation), poly-ip series (manufactured by Idemitsu Kosan Corporation), EPOL (manufactured by Idemitsu Kosan Corporation), etc. are suitably used.

The chain that can be used as R ³ preferably has a mass average molecular weight, etc. (in terms of polystyrene) of 500 to 200,000. The lower limit is preferably 500 or more, more preferably 700 or more, and even more preferably 1,000 or more. As an upper limit, 100,000 or less is preferable, and 10,000 or less is more preferable. The mass average molecular weight, etc. is measured by the method described later on the raw material compound before introduction into the main chain of the polymer.

The content of the component represented by any of the above formulas (1-1) to (1-5) in the polymer is not particularly limited, but is preferably 10 to 100 mol%. The content of the component represented by the above formula (1-1) is more preferably 30 to 98 mol%, and more preferably 50 to 95 mol%, from the viewpoint of dispersion stability, binding properties, etc. The content of the component represented by any of the above formulas (1-2) to (1-5) is more preferably 30 to 98 mol%, and more preferably 50 to 95 mol%, from the viewpoint of dispersion stability, etc. do. On the other hand, in terms of improving binding properties, it is preferable that it is 0 to 90 mol%, more preferably 10 to 80 mol%, and even more preferably 20 to 70 mol%.

(Component having a functional group selected from functional group group (a))

The polymer forming at least one of the polymer binder A and the polymer binder B preferably contains a component having a functional group selected from the following functional group group (a) as a substituent, for example. Among them, it is preferable that the polymer forming polymer binder B contains a component having a functional group selected from the following functional group group (a). The component having a functional group has a function of improving the adsorption rate of the binder and may be any component that forms a polymer. The functional group may be introduced into the main chain of the polymer or may be introduced into the side chain. When introduced into the side chain, the functional group may be directly bonded to the main chain or may be bonded through the linking group. The linking group is not particularly limited, but includes the linking group described later.

<Functional group (a)>

Hydroxyl group, amino group, carboxy group, sulfo group, phosphoric acid group, phosphonic acid group, sulfanyl group, ether bond (-O-), imino group (=NR, -NR-), ester bond (-CO-O-), Amide bond (-CO-NR-), imide group (-CO-NR-CO-), urethane bond (-NR-CO-O-), urea bond (-NR-CO-NR-), heterocyclic group , aryl group, anhydrous carboxylic acid group

Functional group group (a) is a hydroxy group, amino group, carboxy group, sulfo group, phosphoric acid group, phosphonic acid group, sulfanyl group, ether bond, imino group, amide bond, imide group, urethane bond, urea bond, and heterocyclic group. , an aryl group, and an anhydrous carboxylic acid group are preferable.

The amino group, sulfo group, phosphoryl group (phosphoryl group), heterocyclic group, and aryl group included in the functional group group (a) are not particularly limited, but have the same meaning as the corresponding group of the substituent Z described later. However, the number of carbon atoms in the amino group is more preferably 0 to 12, more preferably 0 to 6, and especially preferably 0 to 2. The phosphonic acid group is not particularly limited, but examples include phosphonic acid groups having 0 to 20 carbon atoms. If amino group, ether bond, imino group (-NR-), ester bond, amide bond, imide group, urethane bond, urea bond, etc. are included in the ring structure, it is classified as a heterocycle. The heterocycle containing an imide group in the ring structure is not particularly limited, but includes, for example, an anhydrous carboxylic acid group described later, for example, "-CO-O-CO-" in formula (2a) or formula (2b). Examples include rings in which the group "is changed to "-CO-NR ^I -CO-". Here, R ^I represents a hydrogen atom or a substituent. The substituent is not particularly limited and is selected from the substituent Z described later, and an alkyl group is preferable. The hydroxy group, amino group, carboxy group, sulfo group, phosphoric acid group, phosphonic acid group, and sulphanyl group may form a salt.

R in each bond represents a hydrogen atom or a substituent, and a hydrogen atom is preferable. The substituent is not particularly limited and is selected from the substituent Z described later, and an alkyl group is preferable.

R ^I in the imide group is as described above.

The anhydrous carboxylic acid group is not particularly limited, but is a group formed by removing one or more hydrogen atoms from a carboxylic acid anhydride (for example, a group represented by the following formula (2a)), and further a group formed by copolymerizing a polymerizable carboxylic acid anhydride as a copolymerizable compound. It includes the component itself (for example, the component represented by the following formula (2b)). As the group formed by removing one or more hydrogen atoms from a carboxylic acid anhydride, a group formed by removing one or more hydrogen atoms from a cyclic carboxylic acid anhydride is preferable. Anhydrous carboxylic acid groups derived from cyclic carboxylic acid anhydrides are equivalent to heterocyclic groups, but in the present invention, they are classified as anhydrous carboxylic acid groups. Examples include acyclic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and benzoic acid, and cyclic carboxylic acid anhydrides such as maleic anhydride, phthalic anhydride, fumaric anhydride, and succinic anhydride. The polymerizable carboxylic acid anhydride is not particularly limited, but includes carboxylic acid anhydrides having an unsaturated bond in the molecule, and is preferably a polymerizable cyclic carboxylic acid anhydride. Specifically, maleic anhydride and the like can be mentioned.

Examples of anhydrous carboxylic acid groups include groups represented by the following formula (2a) or components represented by the formula (2b), but the present invention is not limited to these. In each formula, * represents the binding position.

[Formula 2]

In sequential polymerization polymers, ester linkage (-CO-O-), amide linkage (-CO-NR-), urethane linkage (-NR-CO-O-) and urea linkage (-NR-CO-NR- ), when the chemical structure of the polymer is expressed as a component derived from the raw material compound, -CO- group and -O- group, -CO group and -NR- group, -NR-CO-group and -O- It appears divided into group, -NR-CO- group and -NR- group. Therefore, in the present invention, the constituents having these bonds are, regardless of the notation of the polymer, a constituent derived from a carboxylic acid compound or an isocyanate compound, and a constituent derived from a polyol or polyamine compound. do not include

In addition, in the chain polymerization polymer, the constituents having an ester bond (excluding the ester bond forming a carboxy group) include the main chain of the chain polymerization polymer and the polymer chain introduced as a branch or pendant chain into the chain polymerization polymer (e.g. For example, it means a component whose ester bond is not directly bonded to the atom constituting the main chain of the polymer chain of the macromonomer, and does not include components derived from (meth)acrylic acid alkyl ester, for example.

In the present invention, the amino group, ether bond, imino group, ester bond, amide bond, urethane bond, urea bond, heterocyclic group, and aryl group are preferably introduced into the branch chain of the polymer.

One type of functional group may be included in one component, or two or more types may be included. When two or more types of functional groups are present, they may be bonded to each other or not bonded to each other. In addition, the number of functional groups that one component has is not particularly limited, and may be one or more, and may be 1 to 4.

The linking group that bonds the functional group to the main chain is not particularly limited, but other than the following particularly preferred linking groups, it has the same meaning as the linking group in the group having a hydrocarbon group of 4 or more carbon atoms that can be adopted as R ² in the above formula (1-1) am. As a linking group that binds a ^{functional group to the main chain, a particularly preferred linking group is a -CO-O- group or -CO-N(RN)-group (R N is} the same as above) and an alkylene group or polyalkyleneoxy chain. It is a group formed by combining.

The component having the functional group is not particularly limited as long as it has the functional group, but for example, a configuration in which the functional group is introduced into a component represented by any of the above-mentioned formulas (1-1) to (1-5) component, a component represented by formula (I-1) or formula (I-2) described later, a component derived from a compound represented by formula (I-5) described later, and a formula (I-3) or formula described later A component obtained by introducing the above-mentioned functional group into the component represented by (I-4) or a component derived from a compound represented by formula (I-6), furthermore, the (meth)acrylic compound (M1) described later or other polymerizable compounds. (M2), a component obtained by introducing the above functional group into a component represented by any of formulas (b-1) to (b-3) described later, and the like.

The compound from which the component having the above functional group is derived is not particularly limited, but examples include compounds obtained by introducing the above functional group into a (meth)acrylic acid short-chain alkyl ester compound (short-chain alkyl refers to an alkyl group having 3 or less carbon atoms). I can hear it.

The content of the component having the above functional group in the polymer is not particularly limited.

In sequentially polymerized polymers, the content is preferably 0.01 to 50 mol%, more preferably 0.1 to 50 mol%, and even more preferably 0.3 to 50 mol%, from the viewpoint of dispersion characteristics and binding properties of solid particles. . In chain polymerization polymers, from the viewpoint of dispersion characteristics of solid particles, binding properties, etc., the content is preferably 0.01 to 80 mol%, more preferably 0.01 to 70 mol%, and even more preferably 0.1 to 50 mol%. , 0.3 to 50 mol% is particularly preferable. The upper limit of the content may be 30 mol% or less or 10 mol% or less. In sequentially polymerized polymers and chain polymerized polymers, the lower limit of the content may be 1 mol% or more, 5 mol% or more, or 20 mol% or more.

-Sequentially polymerized polymer-

The sequentially polymerized polymer as the polymer forming the binder is a component having a functional group selected from the functional group group (a) described above or a component represented by any of the formulas (1-2) to (1-5) described above. It is preferable to have, and may also have components different from these components. Among the components shown below, the component represented by formula (I-1) or formula (I-2) and the component derived from the compound represented by formula (I-5) have a functional group selected from the functional group group (a). Although the components it has are equivalent, they are explained together with other components. As other components, for example, one or more components represented by the following formula (I-1) or (I-2), and further, one or more components represented by the following formula (I-3) or (I-4) (Preferably 1 to 8 types, more preferably 1 to 4 types), or a diamine compound deriving a carboxylic dianhydride represented by the following formula (I-5) and a component represented by the following formula (I-6) Components formed by sequentially polymerizing include. The combination of each component is appropriately selected depending on the polymer species. One type of component used in the combination of components means a component expressed by one of the formulas below, and even if it contains two types of components expressed by one of the formulas below, it is not interpreted as two types of components. I never do that.

[Formula 3]

In the formula, R ^P1 and R ^P2 each represent a molecular chain having a (mass average) molecular weight of 20 to 200,000. The molecular weight of this molecular chain cannot be determined unilaterally because it depends on its type, etc., but for example, 30 or more is preferable, 50 or more is more preferable, 100 or more is more preferable, and 150 or more is more preferable. Particularly desirable. As an upper limit, 100,000 or less is preferable, and 10,000 or less is more preferable. The molecular weight of the molecular chain is measured for the raw material compound before introduction into the polymer main chain.

The molecular chains that can be taken as R ^P1 and R ^P2 are not particularly limited, but are preferably hydrocarbon chains, polyalkylene oxide chains, polycarbonate chains, or polyester chains, and hydrocarbon chains or polyalkylene oxide chains are preferred. More preferably, a hydrocarbon chain, polyethylene oxide chain or polypropylene oxide chain is more preferable.

The hydrocarbon chain, which can be taken as R ^P1 and R ^P2 , means a hydrocarbon chain composed of carbon atoms and hydrogen atoms, and more specifically, at least two atoms of a compound composed of carbon atoms and hydrogen atoms (e.g. For example, it means a structure in which a hydrogen atom) or a group (for example, a methyl group) is separated. However, in the present invention, the hydrocarbon chain also includes a chain having a group containing an oxygen atom, a sulfur atom, or a nitrogen atom in the chain, such as a hydrocarbon group represented by the following formula (M2). Terminal groups that may be present at the ends of the hydrocarbon chain are not included in the hydrocarbon chain. This hydrocarbon chain may have a carbon-carbon unsaturated bond and may have a ring structure of an aliphatic ring and/or an aromatic ring. That is, the hydrocarbon chain may be a hydrocarbon chain composed of a hydrocarbon selected from aliphatic hydrocarbons and aromatic hydrocarbons.

Such a hydrocarbon chain may be any one that satisfies the above-mentioned molecular weight, and includes both a chain composed of a low molecular weight hydrocarbon group and a hydrocarbon chain composed of a hydrocarbon polymer (also referred to as a hydrocarbon polymer chain). .

The low molecular weight hydrocarbon chain is a chain composed of ordinary (non-polymerizable) hydrocarbon groups. Examples of this hydrocarbon group include an aliphatic or aromatic hydrocarbon group, and specifically, an alkylene group (carbon number is preferably 1 to 12, more preferably 1 to 6, and more preferably 1 to 3), an arylene group (the number of carbon atoms is preferably 6 to 22, preferably 6 to 14, and more preferably 6 to 10). ), or a group consisting of a combination of these is preferable. As the hydrocarbon group forming the low molecular weight hydrocarbon chain that can be taken as R ^P2 , an alkylene group is more preferable, an alkylene group with 2 to 6 carbon atoms is more preferable, and an alkylene group with 2 or 3 carbon atoms is particularly preferable. . This hydrocarbon chain may have a polymer chain (for example, (meth)acrylic polymer) as a substituent.

The aliphatic hydrocarbon group is not particularly limited and includes, for example, a hydrogen reducing product of an aromatic hydrocarbon group represented by the formula (M2) below, and a partial structure possessed by known aliphatic diisocyanate compounds (e.g. Group consisting of isophorone) etc. can be mentioned.

Examples of the aromatic hydrocarbon group include the hydrocarbon group of each of the exemplary components described below, and an arylene group (for example, one hydrogen atom is added from the aryl group represented by the substituent Z described later). The group removed above (specifically, a phenylene group, tolylene group, or xylylene group) or a hydrocarbon group represented by the following formula (M2) is preferable.

[Formula 4]

_In formula ( _{M2 ) ,} -CH ₂ - or -O- is preferred, and -CH ₂ - is more preferred. The alkylene group and methyl group exemplified here may be substituted with a substituent Z, preferably a halogen atom (more preferably a fluorine atom).

R ^M2 to R ^M5 each represent a hydrogen atom or a substituent, and a hydrogen atom is preferable. Substituents that can be used as R ^M2 to R ^M5 are not particularly limited, and examples include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, -OR ^M6 , -N(R ^M6 ) ₂ , and -SR. ^M6 (R ^M6 represents a substituent, preferably an alkyl group with 1 to 20 carbon atoms or an aryl group with 6 to 10 carbon atoms), a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom). You can. -N(R ^M6 ) ₂ is an alkylamino group (preferably 1 to 20 carbon atoms, more preferably 1 to 6) or an arylamino group (preferably 6 to 40 carbon atoms, more preferably 6 to 20 carbon atoms). do) can be mentioned.

The hydrocarbon polymer chain is a polymer chain formed by polymerizing (at least two) polymerizable hydrocarbons, and is not particularly limited as long as it is a chain made of a hydrocarbon polymer with a larger number of carbon atoms than the low molecular weight hydrocarbon chain described above, but is preferred. is a chain made of a hydrocarbon polymer consisting of 30 or more carbon atoms, more preferably 50 or more carbon atoms. The upper limit of the number of carbon atoms constituting the hydrocarbon polymer is not particularly limited and can be, for example, 3,000. This hydrocarbon polymer chain is preferably a chain made of a hydrocarbon polymer composed of an aliphatic hydrocarbon whose main chain satisfies the above-mentioned number of carbon atoms, and a polymer composed of an aliphatic saturated hydrocarbon or an aliphatic unsaturated hydrocarbon (preferably It is more preferable that it is a chain made of elastomer). Specific examples of the polymer include diene-based polymers that have a double bond in the main chain, and non-diene-based polymers that do not have a double bond in the main chain. Examples of the diene polymer include styrene-butadiene copolymer, styrene-ethylene-butadiene copolymer, copolymer of isobutylene and isoprene (preferably butyl rubber (IIR)), Ethylene-propylene-diene copolymer, etc. can be mentioned. Examples of non-diene polymers include olefin polymers such as ethylene-propylene copolymer and styrene-ethylene-butylene copolymer, and hydrogen reduction products of the diene polymers.

The hydrocarbon that becomes the hydrocarbon chain preferably has a reactive group at its terminal, and more preferably has a terminal reactive group capable of condensation polymerization. The terminal reactive group capable of condensation polymerization or polyaddition forms a group that binds to R ^P1 or R ^P2 of each of the above formulas by condensation polymerization or polyaddition. Examples of such terminal reactive groups include isocyanate groups, hydroxy groups, carboxyl groups, amino groups, and acid anhydrides, and among them, hydroxy groups are preferable.

Examples of the hydrocarbon polymer having a terminal reactive group include the NISSO-PB series (manufactured by Nippon Soda Corporation), the Claysol series (manufactured by Tomoe Industries), the PolyVEST-HT series (manufactured by Evonik Corporation), and the poly-bd series. (manufactured by Idemitsu Kosan Corporation), poly-ip series (manufactured by Idemitsu Kosan Corporation), EPOL (manufactured by Idemitsu Kosan Corporation), and polytail series (manufactured by Mitsubishi Chemical Corporation) are suitably used.

Examples of the polyalkylene oxide chain (polyalkylene oxy chain) include chains composed of known polyalkylene oxy groups. The number of carbon atoms of the alkyleneoxy group in the polyalkyleneoxy chain is preferably 1 to 10, more preferably 1 to 6, and more preferably 2 or 3 (polyethyleneoxy chain or polypropyleneoxy chain). The polyalkyleneoxy chain may be a chain composed of one type of alkyleneoxy group, or may be a chain composed of two or more types of alkyleneoxy groups (for example, a chain composed of an ethyleneoxy group and a propyleneoxy group).

Examples of the polycarbonate chain or polyester chain include chains made of known polycarbonate or polyester.

The polyalkyleneoxy chain, polycarbonate chain, or polyester chain preferably has an alkyl group at the terminal (carbon number is preferably 1 to 12, more preferably 1 to 6).

The terminals of the polyalkyleneoxy chain, polycarbonate chain, and polyester chain that can be taken ^as R P1 and R ^P2 can be appropriately changed to common chemical structures that can be introduced into the components represented by the above formulas as R ^P1 and R ^P2 . You can. For example, the polyalkyleneoxy chain is introduced as R ^P1 or R ^P2 of the above constituent by removing the terminal oxygen atom.

Inside or at the end of the alkyl group contained in the molecular chain, an ether group (-O-), a thioether group (-S-), a carbonyl group (>C=O), an imino group (>NR ^N : R ^N is a hydrogen atom , an alkyl group with 1 to 6 carbon atoms or an aryl group with 6 to 10 carbon atoms).

In each of the above formulas, R ^P1 and R ^P2 are divalent molecular chains, but at least one hydrogen atom is substituted with -NH-CO-, -CO-, -O-, -NH- or -N<, thereby forming a trivalent molecular chain. The above molecular chain may be formed.

Among the above molecular chains, R ^P1 is preferably a hydrocarbon chain, more preferably a low molecular weight hydrocarbon chain, more preferably a hydrocarbon chain composed of an aliphatic or aromatic hydrocarbon group, and more preferably an aliphatic hydrocarbon group. A hydrocarbon chain consisting of a hydrocarbon chain is particularly preferred.

Among the above molecular chains, R ^P2 is a low molecular weight hydrocarbon chain (more preferably an aliphatic hydrocarbon group) or a molecular chain other than a low molecular weight hydrocarbon chain (more preferably a polyalkylene oxide chain). desirable.

Specific examples of the components represented by the formula (I-1) are shown below and in the Examples. In addition, as a raw material compound (diisocyanate compound) from which the component represented by the formula (I-1) is derived, for example, diamond represented by the formula (M1) described in International Publication No. 2018/020827 Isocyanate compounds and their specific examples, further examples include polymeric 4,4'-diphenylmethane diisocyanate. In addition, in the present invention, the constituents represented by formula (I-1) and the raw material compounds from which they are derived are not limited to those described in the following specific examples, examples, and the above literature.

[Formula 5]

The raw material compound (carboxylic acid or its acid chloride, etc.) deriving the component represented by the above formula (I-2) is not particularly limited, and for example, described in paragraph [0074] of International Publication No. 2018/020827, Compounds of carboxylic acid or acid chloride and specific examples thereof (for example, adipic acid or its esterate) can be given.

Specific examples of the components represented by the formula (I-3) or formula (I-4) are shown below and in the Examples. In addition, the raw material compounds (diol compounds or diamine compounds) from which the constituents represented by the formula (I-3) or (I-4) are derived are not particularly limited, and are, for example, International Publication Publication No. Each compound described in No. 2018/020827 and its specific examples may be mentioned, and dihydroxyoxamide may also be mentioned. In addition, in the present invention, the constituents represented by formula (I-3) or formula (I-4) and the raw material compounds deriving them are not limited to the following specific examples, the following exemplary polymers, examples, and those described in the above literature. No.

In addition, in the following specific examples, when there is a repeating structure among the constituents, the number of repeats is an integer of 1 or more, and is appropriately set in a range that satisfies the molecular weight or number of carbon atoms of the molecular chain.

[Formula 6]

In formula (I-5), R ^P3 represents an aromatic or aliphatic linking group (tetravalent), and a linking group represented by any of the following formulas (i) to (iix) is preferable.

[Formula 7]

In formulas (i) to (iix), X ¹ represents a single bond or a divalent linking group. As the divalent linking group, an alkylene group having 1 to 6 carbon atoms (for example, methylene, ethylene, propylene) is preferable. As propylene, 1,3-hexafluoro-2,2-propanediyl is preferable. L represents -CH ₂ =CH ₂ - or -CH ₂ -. ^{R _} In each formula, * represents the binding site with the carbonyl group in formula (I-5). Substituents that can ^be employed as ^R more preferable) or an aryl group (carbon number is preferably 6 to 22, more preferably 6 to 14, and more preferably 6 to 10).

The carboxylic acid dianhydride represented by the above formula (I-5) and the raw material compound (diamine compound) from which the component represented by the above formula (I-6) is derived are not particularly limited, and include, for example, international publications. Each compound and its specific examples described in Publication No. 2018/020827 and International Publication No. 2015/046313 can be mentioned.

R ^P1 , R ^P2 and R ^P3 may each have a substituent. This substituent is not particularly limited and includes, for example, the substituent Z described later, or each group included in the functional group group (a), and suitable examples include the substituent mentioned above that can be employed as R ^M2 .

When the polymer forming the binder is a sequentially polymerized polymer, a component represented by any one of the above-mentioned formulas (1-1) to (1-5), preferably a component having a functional group selected from the functional group group (a) It has a component (including a component represented by the formula (I-1) below), and also has a component represented by the formula (I-3), formula (I-4), or formula (I-5) above. You can stay. Examples of the component represented by formula (I-3) include components represented by at least one of the following formulas (I-3A) to (I-3C). The component represented by formula (I-4) is the same as the component represented by formula (I-3), but in each of the following formulas (I-3A) to (I-3C), oxygen atoms are replaced with nitrogen atoms. Substitute.

[Formula 8]

In formula (I-1), R ^P1 is as described above. In formula (I-3A), R ^P2A represents a chain consisting of a low molecular weight hydrocarbon group (preferably an aliphatic hydrocarbon group). In formula (I-3B), R ^P2B represents a polyalkyleneoxy chain. In formula (I-3C), R ^P2C represents a hydrocarbon polymer chain. The chain consisting of a low molecular weight hydrocarbon group that can be represented as R ^P2A , the polyalkyleneoxy chain that can be represented as R ^P2B , and the hydrocarbon polymer chain that can be represented as R ^P2C are, respectively, in the above formula (I-3). It has the same meaning as the aliphatic hydrocarbon group, polyalkyleneoxy chain, and hydrocarbon polymer chain that can be taken as R ^P2 , and is also preferred.

The polymer (sequentially polymerized polymer) forming the binder may have components other than those expressed by the formulas above. Such components are not particularly limited as long as they can be sequentially polymerized with the raw material compounds that derive the components represented by each of the above formulas.

The (total) content of the components represented by the formulas (I-1) to (I-6) in the polymer forming the binder is not particularly limited, but is preferably 5 to 100 mol%, and 5 to 80 mol%. It is more preferable that it is mol%, and it is more preferable that it is 10-60 mol%. The upper limit of this content may be, for example, 100 mol% or less, regardless of the above 60 mol%.

The content of components other than the components represented by each of the above formulas in the polymer forming the binder is not particularly limited, but is preferably 50 mol% or less.

When the polymer forming the binder has a component represented by any of the formulas (I-1) to (I-6), the content is not particularly limited and is appropriately selected, for example, as follows: It can be set to a range.

In other words, the content of the component represented by formula (I-1) or formula (I-2) or the component derived from carboxylic dianhydride represented by formula (I-5) in the polymer forming the binder is particularly limited. However, it is preferable that the content is the same as the content of the components having functional groups described above.

The content of the component represented by formula (I-3), formula (I-4) or formula (I-6) in the polymer forming the binder is not particularly limited, and is preferably 1 to 80 mol%. , it is more preferable that it is 10-80 mol%, it is more preferable that it is 20-70 mol%, and it is especially preferable that it is 30-60 mol%.

The content of each component represented by any of the above formulas (I-3A) to (I-3C) is appropriately set in consideration of the content of each component represented by the above formula (I-3).

In addition, when the polymer forming the binder has a plurality of constituents represented by each formula, the above content of each constituent is taken as the total content.

The polymer (each component and raw material compound) forming the binder may have a substituent. The substituent is not particularly limited, but preferably includes a group selected from the substituent Z below.

The polymer forming the binder can be synthesized by selecting a raw material compound according to the type of bond the main chain has by a known method and subjecting the raw material compound to polyaddition or condensation polymerization. As a synthesis method, for example, reference can be made to International Publication No. 2018/151118.

The method for introducing a functional group is not particularly limited and includes, for example, a method of copolymerizing a compound having a functional group selected from the functional group group (a), a method of using a polymerization initiator having (generating) the functional group, and a polymer reaction. How to use it, etc.

Polymers of polyurethane, polyurea, polyamide, and polyimide that can be used as polymers forming the binder include, for example, those synthesized in the example polymers and examples described below. Each polymer described in 2018/020827 and International Publication No. 2015/046313, and further Japanese Patent Publication No. 2015-088480, etc. can be mentioned.

-Substituent Z-

Alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2-ethoxyethyl, 1-carboxymethyl, etc.), Alkenyl group (preferably an alkenyl group with 2 to 20 carbon atoms, such as vinyl, allyl, oleyl, etc.), an alkynyl group (preferably an alkynyl group with 2 to 20 carbon atoms, such as ethyneyl) , butadiynyl, phenylethanyl, etc.), cycloalkyl groups (preferably cycloalkyl groups with 3 to 20 carbon atoms, for example, cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc., in the present invention. When referring to an alkyl group, it usually includes a cycloalkyl group, but is described separately here.), an aryl group (preferably an aryl group with 6 to 26 carbon atoms, for example, phenyl, 1-naphthyl, 4-methoxy) phenyl, 2-chlorophenyl, 3-methylphenyl, etc.), aralkyl group (preferably an aralkyl group with 7 to 23 carbon atoms, such as benzyl, phenethyl, etc.), heterocyclic group (preferably a heterocyclic group with 2 to 20 carbon atoms) It is a 5- or 6-membered heterocyclic group having at least one oxygen atom, a sulfur atom, and a nitrogen atom. The heterocyclic group includes an aromatic heterocyclic group and an aliphatic heterocyclic group. For example, tetrahydrocyclic group. Pyran group, tetrahydrofuran group, 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, pyrrolidone group, etc.), alkoxy group (Preferably an alkoxy group having 1 to 20 carbon atoms, such as methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), an aryloxy group (preferably an aryloxy group having 6 to 26 carbon atoms, such as , phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc.), heterocyclic oxy group (a group in which -O- group is bonded to the heterocyclic group), alkoxycarbonyl group (preferably Alkoxycarbonyl group having 2 to 20 carbon atoms, such as ethoxycarbonyl, 2-ethylhexyloxycarbonyl, dodecyloxycarbonyl, etc.), aryloxycarbonyl group (preferably aryloxycarbonyl group having 6 to 26 carbon atoms) Nyl group, such as phenoxycarbonyl, 1-naphthyloxycarbonyl, 3-methylphenoxycarbonyl, 4-methoxyphenoxycarbonyl, etc.), heterocyclic oxycarbonyl group (-O to the heterocyclic group) -CO-group bonded group), amino group (preferably including amino group, alkylamino group, and arylamino group having 0 to 20 carbon atoms, for example, amino (-NH ₂ ), N, N-dimethylamino, N, N-diethylamino, N-ethylamino, anilino, etc.), sulfamoyl group (preferably a sulfamoyl group with 0 to 20 carbon atoms, for example, N,N-dimethylsulfamoyl, N-phenylsulfamoyl) etc.), acyl groups (including alkyl carbonyl groups, alkenyl carbonyl groups, alkynyl carbonyl groups, aryl carbonyl groups, and heterocyclic carbonyl groups, preferably acyl groups having 1 to 20 carbon atoms, such as acetyl, Propionyl, butyryl, octane oil, hexadecane oil, acryloyl, methacryloyl, crotonoyl, benzoyl, naphthoyl, nicotine oil, etc.), acyloxy group (alkylcarbonyloxy group, alkenylcarbonyloxy group) , an alkynylcarbonyloxy group, a heterocyclic carbonyloxy group, and preferably an acyloxy group having 1 to 20 carbon atoms, such as acetyloxy, propionyloxy, butyryloxy, octanoyloxy, and hexadecane. oiloxy, acryloyloxy, methacryloyloxy, crotonoyloxy, nicotine oiloxy, etc.), aryloyloxy group (preferably an aryloyloxy group with 7 to 23 carbon atoms, for example, benzoyloxy, naphthoyloxy, etc.), carbamoyl group (preferably a carbamoyl group with 1 to 20 carbon atoms, for example, N, N-dimethylcarbamoyl, N-phenylcarbamoyl, etc.), acylamino group (preferably with 1 to 20 carbon atoms) Acylamino groups of 1 to 20 carbon atoms, such as acetylamino, benzoylamino, etc.), alkyl thio groups (preferably alkyl thio groups of 1 to 20 carbon atoms, such as methyl thio, ethyl thio, and isopropyl thio groups. 5, benzylthio, etc.), arylthio group (preferably an arylthio group with 6 to 26 carbon atoms, for example, phenylthio, 1-naphthylthio, 3-methylphenylthio, 4-methoxyphenyl) thio, etc.), heterocyclic thio group (a group in which -S- group is bonded to the heterocyclic group), alkyl sulfonyl group (preferably an alkyl sulfonyl group with 1 to 20 carbon atoms, for example, methyl sulfonyl, ethyl sulfonyl) etc.), arylsulfonyl group (preferably an arylsulfonyl group with 6 to 22 carbon atoms, for example, benzenesulfonyl, etc.), an alkylsilyl group (preferably an alkylsilyl group with 1 to 20 carbon atoms, for example, mono methylsilyl, dimethylsilyl, trimethylsilyl, triethylsilyl, etc.), arylsilyl group (preferably an arylsilyl group with 6 to 42 carbon atoms, for example, triphenylsilyl, etc.), alkoxysilyl group (preferably Alkoxysilyl group having 1 to 20 carbon atoms, for example, monomethoxysilyl, dimethoxysilyl, trimethoxysilyl, triethoxysilyl, etc.), aryloxysilyl group (preferably aryloxy silyl group having 6 to 42 carbon atoms) Silyl group, such as triphenyloxysilyl, etc.), phosphoryl group (preferably a phosphoric acid group having 0 to 20 carbon atoms, such as -OP(=O)(R ^P ) ₂ ), phosphonyl group (preferably Examples include a phosphonyl group having 0 to 20 carbon atoms, such as -P(=O)(R ^P ) ₂ ), a phosphine group (preferably a phosphenyl group having 0 to 20 carbon atoms, such as -P (R ^P ) ₂ ), phosphonic acid group (preferably a phosphonic acid group having 0 to 20 carbon atoms, for example -PO(OR ^P ) ₂ ), a sulfo group (sulfonic acid group), a carboxy group, a hydroxy group, Examples include a sulfanyl group, a cyano group, and a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.). R ^P is a hydrogen atom or a substituent (preferably a group selected from substituent Z).

In addition, each group included in these substituents Z may have the substituent Z further substituted.

The alkyl group, alkylene group, alkenyl group, alkenylene group, alkynyl group, and/or alkynylene group may be cyclic, chain-shaped, straight-chain, or branched.

-Chain polymerization polymer-

A chain polymerization polymer as a polymer forming the binder will be described.

The chain polymerization polymer preferably has a component having a functional group selected from the functional group group (a) described above or a component represented by the formula (1-1) described above, and a component having the functional group and formula (1) It is more preferable to have the constituents represented by -1), and it may further have constituents different from these constituents. The chain polymerization polymer may be a polymer that does not have a component having a functional group selected from the functional group group (a) or a component represented by the above-mentioned formula (1-1), but consists of other components.

Examples of fluorinated polymers include polytetrafluoroethylene (PTFE), polyvinylene difluoride (PVdF), copolymer of polyvinylidene difluoride and hexafluoropropylene (PVdF-HFP), and poly Examples include vinylidene difluoride and a copolymer of hexafluoropropylene and tetrafluoroethylene (PVdF-HFP-TFE). In PVdF-HFP, the copolymerization ratio [PVdF:HFP] (mass ratio) of PVdF and HFP is not particularly limited, but is preferably 9:1 to 5:5, and 9:1 to 7:3 from the viewpoint of adhesion. It is more desirable. In PVdF-HFP-TFE, the copolymerization ratio [PVdF:HFP:TFE] (mass ratio) of PVdF, HFP, and TFE is not particularly limited, but is preferably 20 to 60:10 to 40:5 to 30, and 25 ~50:10~35:10~25 is more preferable.

Hydrocarbon polymers include, for example, polyethylene, polypropylene, natural rubber, polybutadiene, polyisoprene, polystyrene, polystyrene-butadiene copolymer, styrene-based thermoplastic elastomer, polybutylene, and acrylonitrile-butadiene copolymer. These include polymers or hydrogenated (hydrogenated) polymers thereof. The styrene-based thermoplastic elastomer or its hydride is not particularly limited, but examples include styrene-ethylene-butylene-styrene block copolymer (SEBS) and styrene-isoprene-styrene block copolymer (SIS). , hydrogenated SIS, styrene-butadiene-styrene block copolymer (SBS), hydrogenated SBS, styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-ethylene-propylene-styrene. Block copolymers (SEPS), styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber (HSBR), and even random copolymers corresponding to the above block copolymers such as SEBS, etc. there is. In the present invention, it is preferable that the hydrocarbon polymer does not have an unsaturated group (for example, a 1,2-butadiene component) bonded to the main chain because it can suppress the formation of chemical crosslinks.

Examples of the vinyl polymer include polymers containing, for example, 50 mol% or more of vinyl monomers other than the (meth)acrylic compound (M1). Examples of vinyl monomers include vinyl compounds described later. Specific examples of the vinyl polymer include polyvinyl alcohol, polyvinyl acetal, polyvinyl acetate, and copolymers containing these.

This vinyl polymer also preferably has, in addition to components derived from vinyl monomers, components derived from a (meth)acrylic compound (M1) that forms the (meth)acrylic polymer described later. The content of the constituents derived from the vinyl monomer is preferably the same as the content of the constituents derived from the (meth)acrylic compound (M1) in the (meth)acrylic polymer. The content of the component derived from the (meth)acrylic compound (M1) is not particularly limited as long as it is less than 50 mol% in the polymer, but is preferably 0 to 30 mol%.

As the (meth)acrylic polymer, as another component, at least one (meth)acrylic acid compound, (meth)acrylic acid ester compound, (meth)acrylamide compound, and (meth)acrylonitrile compound is selected. A polymer obtained by copolymerizing an acrylic compound (M1) is preferred. Moreover, a (meth)acrylic polymer consisting of a copolymer of a (meth)acrylic compound (M1) and another polymerizable compound (M2) is also preferable. Other polymerizable compounds (M2) are not particularly limited and include styrene compounds, vinyl naphthalene compounds, vinyl carbazole compounds, allyl compounds, vinyl ether compounds, vinyl ester compounds, dialkyl itaconic acid compounds, unsaturated carboxylic acid anhydrides, etc. vinyl compounds, and fluorinated products thereof. Examples of vinyl compounds include "vinyl-based monomer" described in Japanese Patent Application Laid-Open No. 2015-88486.

The (meth)acrylic compound (M1) and other polymerizable compounds (M2) may have a substituent. The substituent is not particularly limited as long as it is a group other than the functional group included in the above-mentioned functional group group (a), and preferably includes a group selected from the above substituent Z.

The content of other polymerizable compounds (M2) in the (meth)acrylic polymer is not particularly limited, but can be, for example, 50 mol% or less.

As the (meth)acrylic compound (M1) and vinyl compound (M2) from which the constituents of the (meth)acrylic polymer and vinyl polymer are derived, a compound represented by the following formula (b-1) is preferable. This compound is different from the component having a functional group included in the functional group group (a) described above and the compound deriving the component represented by the above formula (1-1).

[Formula 9]

In the formula, R ¹ is a hydrogen atom, a hydroxy group, a cyano group, a halogen atom, an alkyl group (preferably 1 to 24 carbon atoms, more preferably 1 to 12 carbon atoms, and especially preferably 1 to 6 carbon atoms), or an alkenyl group. (Preferred carbon atoms are 2 to 24, more preferred are 2 to 12, and particularly preferred are 2 to 6), alkyneyl group (preferred are carbon atoms 2 to 24, more preferred are 2 to 12, and 2 to 6 are preferred). particularly preferred), or an aryl group (preferably 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms). Among them, a hydrogen atom or an alkyl group is preferable, and a hydrogen atom or a methyl group is more preferable.

R ² represents a hydrogen atom or a substituent. The substituent that can be used as R ² is not particularly limited, but includes an alkyl group (branched chain may be used, but a straight chain is preferable), an alkenyl group (carbon number 2 to 12 is preferable, 2 to 6 is more preferable, and 2 or 3 is particularly preferable). preferred), an aryl group (preferably 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms), an aralkyl group (preferably 7 to 23 carbon atoms, more preferably 7 to 15 carbon atoms), and a cyano group. .

The alkyl group preferably has 1 to 3 carbon atoms. For example, the alkyl group may have groups other than the functional groups included in the functional group group (a) among the substituents Z described above.

L ¹ is a linking group and is not particularly limited, but includes, for example, an alkylene group having 1 to 6 carbon atoms (preferably 1 to 3), an alkenylene group having 2 to 6 carbon atoms (preferably 2 to 3), or a carbon number. 6 to 24 (preferably 6 to 10) arylene group, oxygen atom, sulfur atom, imino group (-NR ^N -: R ^N is as described above), carbonyl group, phosphoric acid linking group (-OP(OH) (O)-O-), a phosphonic acid linking group (-P(OH)(O)-O-), or a combination thereof, -CO-O- group, -CO-N(R ^N )-group (R ^N is as described above) is preferred. The linking group may have any substituent. The number of atoms constituting the linking group and the number of linking atoms are as described later. Optional substituents include the above-described substituent Z, and examples include an alkyl group or a halogen atom.

n is 0 or 1, with 1 being preferred. However, when -(L ¹ ) _n -R ² represents one type of substituent (for example, an alkyl group), n is set to 0 and R ² is set to a substituent (alkyl group).

Preferred examples of the (meth)acrylic compound (M1) include compounds represented by the following formula (b-2) or (b-3). These compounds are different from the constituents having functional groups included in the above-mentioned functional group group (a) and the compounds deriving the constituents represented by the above formula (1-1).

[Formula 10]

R ¹ and n have the same meaning as in formula (b-1) above.

R ³ has the same meaning as R ² .

L ² is a linking group and has the same meaning as L ¹ above.

L ³ is a linking group and has the same meaning as L ¹ above, but is preferably an alkylene group having 1 to 6 carbon atoms (preferably 1 to 3 carbon atoms).

m is an integer of 1 to 200, preferably an integer of 1 to 100, and more preferably an integer of 1 to 50.

In the above formulas (b-1) to (b-3), the carbon atom that forms the polymerizable group and to which R ¹ is not bonded is represented as an unsubstituted carbon atom (H ₂ C=), but has a substituent. You can have it. The substituent is not particularly limited, but examples include the above-mentioned groups that can be used as R ¹ .

Additionally, in formulas (b-1) to (b-3), groups that may have substituents such as alkyl groups, aryl groups, alkylene groups, and arylene groups have substituents within the range that does not impair the effect of the present invention. You can stay. The substituent may be any substituent other than the functional group selected from the functional group group (a), for example, a group selected from the substituent Z described later, and specific examples include a halogen atom.

The (meth)acrylic polymer preferably has a component having a functional group selected from the functional group group (a) described above or a component represented by the formula (1-1) described above, and the (meth)acrylic compound (M1) ) derived components, components derived from the vinyl compound (M2), and other components copolymerizable with compounds deriving these components. From the viewpoint of dispersion stability and binding properties, it is preferable to have a component represented by the above-mentioned formula (1-1) and a component having a functional group selected from the functional group group (a) among the (meth)acrylic compounds (M1). do.

The chain polymerization polymer (each component and raw material compound) may have a substituent. The substituent is not particularly limited, and preferably includes a group selected from the substituent Z described above, and groups other than the functional groups included in the functional group group (a) described above are preferable.

The content of the constituents in the (meth)acrylic polymer is not particularly limited and is appropriately selected, for example, can be set in the following range. The content of the component represented by the above-mentioned formula (1-1) and the component having a functional group selected from the functional group group (a) is as described above.

The content of the component derived from the (meth)acrylic compound (M1) in the (meth)acrylic polymer is not particularly limited and may be 100 mol%, but is preferably 1 to 90 mol%, and is preferably 10 to 80 mol%. It is more preferable that it is mol%, and it is especially preferable that it is 20-70 mol%.

The content of the component derived from the vinyl compound (M2) in the (meth)acrylic polymer is not particularly limited, but is preferably 1 to 50 mol%, more preferably 10 to 50 mol%, and 20 to 50 mol%. Mol% is particularly preferred.

The chain polymerization polymer (each component and raw material compound) may have a substituent. The substituent is not particularly limited as long as it is a group other than the functional group included in the above-mentioned functional group group (a), and preferably includes a group selected from the above substituent Z.

A chain polymerization polymer can be synthesized by selecting a raw material compound and polymerizing the raw material compound according to a known method.

The method for introducing a functional group is not particularly limited and includes, for example, a method of copolymerizing a compound having a functional group selected from functional group group (a), a method of using a polymerization initiator or a chain transfer agent having (generating) the functional group, A method using a polymer reaction, an ene reaction for a double bond (for example, if it is a fluoropolymer, it is formed by dehydrogenation reaction of the VDF component), an ene-thiol reaction, or ATRP (Atom Transfer) using a copper catalyst. Radical Polymerization (Radical Polymerization) polymerization method, etc. In addition, a functional group can be introduced using a functional group present in the main chain, side chain, or terminal of the polymer as a reaction point. For example, using a compound having a functional group, a functional group selected from the functional group group (a) can be introduced through various reactions with the carboxylic acid anhydride group in the polymer chain.

Specific examples of the polymer forming polymer binder A or B include those shown below in addition to those synthesized in the examples, but the present invention is not limited to these. In each specific example, the number attached to the lower right of the component indicates the content in the polymer, and the unit is mol%.

[Formula 11]

Polymer binders A and B can be selected from appropriate polymers as long as they meet the solubility and adsorption rates. For example, the polymer forming the polymer binder A is preferably a polymer having at least one bond among a urethane bond, a urea bond, an amide bond, an imide bond, and an ester bond in the main chain, and a urethane bond A polymer having a main chain is more preferable. The polymer forming the polymer binder B is preferably a polymer having a polymer chain of carbon-carbon double bonds in the main chain, and more preferably a (meth)acrylic polymer. In addition, the combination of the polymer forming polymer binder A and the polymer forming polymer binder B is determined appropriately, and polymers of the same type can be used, but polymers of different types (for example, polymers with different main chain chemical structures) can be used. It is preferable to use, and specifically, a combination of preferable elements of each polymer is preferably used.

(Polymer binders A and B, or the physical properties or characteristics of the polymer forming these binders, etc.)

Polymer binder A or B, or the polymer forming polymer binder A or B, preferably has the following physical properties or characteristics.

The mass average molecular weight of the polymer forming the polymer binder A is not particularly limited, but for example, it is preferably 15,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more. As an upper limit, 5,000,000 or less is practical, but 4,000,000 or less is preferable, 3,000,000 or less is more preferable, and can also be set to 200,000 or less. On the other hand, the mass average molecular weight of the polymer forming the polymer binder B is not particularly limited, but for example, it is preferably 15,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more. As an upper limit, 5,000,000 or less is practical, but 4,000,000 or less is preferable, 3,000,000 or less is more preferable, and can also be set to 200,000 or less.

In addition, the mass average molecular weight of the polymer can be adjusted appropriately by changing the type and content of the polymerization initiator, polymerization time, polymerization temperature, etc.

-Measurement of molecular weight-

In the present invention, unless otherwise specified, the molecular weight of polymers, polymer chains, polymer chains, and macromonomers refers to the mass average molecular weight or number average molecular weight converted to standard polystyrene by gel permeation chromatography (GPC). The measurement method basically includes a method set to the following condition 1 or condition 2 (priority). However, depending on the type of polymer, polymer chain, or macromonomer, an appropriate eluent may be selected and used.

(Condition 1)

Column: Connect two TOSOH TSKgel Super AWM-H (product name, Tosoh Corporation)

Carrier: 10mMLiBr/N-methylpyrrolidone

Measurement temperature: 40℃

Carrier flow rate: 1.0ml/min

Sample concentration: 0.1 mass%

Detector: RI (refractive index) detector

(Condition 2)

Column: Use a column connecting TOSOH TSKgel Super HZM-H, TOSOH TSKgel Super HZ4000, and TOSOH TSKgel Super HZ2000 (all brand names, manufactured by Tosoh Corporation).

Carrier: tetrahydrofuran

Measurement temperature: 40℃

Carrier flow rate: 1.0ml/min

Sample concentration: 0.1 mass%

Detector: RI (refractive index) detector

The adsorption rate of the polymer binders A and B to the conductive additive described later is not particularly limited, and since the conductive additive has a small content with respect to the active material (AC) and the inorganic solid electrolyte (SE), its dispersion characteristics and binding properties are not particularly limited. The influence on the conductive additive is small, so there is no need to set the adsorption rate for the conductive additive to a specific range.

The moisture concentration of the polymer is preferably 100 ppm (by mass) or less. In addition, the polymer binders A and B may be crystallized and dried polymers, or the polymer solution may be used as is.

The polymers forming polymer binders A and B are preferably amorphous. In the present invention, when a polymer is "amorphous," it typically means that an endothermic peak resulting from crystal melting is not visible when measured by glass transition temperature.

The polymers forming polymer binders A and B may be non-crosslinked polymers or crosslinked polymers. In addition, when crosslinking of the polymer progresses by heating or application of voltage, the molecular weight may be greater than the above molecular weight. Preferably, the polymer has a mass average molecular weight in the above range when use of the all-solid-state secondary battery begins.

The total content of the polymer binder (PB) in the electrode composition is not particularly limited and is appropriately set, for example, 0.3 to 3.0% by mass based on 100% by mass of solid content.

The total content of polymer binders A and B in the electrode composition is appropriately set depending on the content of each polymer binder, and in order to achieve both low resistance and dispersion characteristics and binding properties, for example, solid content is 100 mass. Of the %, it can be 0.5 to 2.0 mass %, preferably 0.5 to 1.5 mass %, and more preferably 0.5 to 1.0 mass %.

The content of polymer binder A and the content of polymer binder B in the electrode composition are not particularly limited and are set appropriately. The amount may be set, for example, taking into account the dispersion characteristics and binding properties of the polymer binder A or B. In this case, it is based on 100 parts by mass of the active material (AC) or inorganic solid electrolyte (SE) contained in the electrode composition. , can be set to 2.0 parts by mass or less, preferably 0.3 to 1.5 parts by mass, and more preferably 0.5 to 1.0 parts by mass.

The content of polymer binder A in the electrode composition may be set to be greater than the content of polymer binder B because it adsorbs the active material (AC), which is generally contained in large quantities in the electrode composition. Specifically, low resistance and (especially From the viewpoint of being compatible with the dispersion characteristics and binding properties of the polymer binder A, it is preferably 0.1 to 3.0% by mass, more preferably 0.3 to 3.0% by mass, and 0.5 to 1.5% by mass, based on 100% by mass of solid content. It is more preferable, and it is especially preferable that it is 0.5-1.0 mass %. In addition, the content of polymer binder B in the electrode composition is specifically, in that low resistance, dispersion characteristics and binding properties (especially of polymer binder B) are compatible, for example, solid content is 100% by mass. Among them, it is preferably 0.1 to 2.0 mass%, more preferably 0.2 to 1.5 mass%, and even more preferably 0.2 to 1.0 mass%.

The difference between the content of polymer binder A and the content of polymer binder B (content of polymer binder A - content of polymer binder B), and the ratio of the content of polymer binder A to the content of polymer binder B (content of polymer binder A / The content of the polymer binder B is not particularly limited and is appropriately set depending on the content of the active material (AC) or the inorganic solid electrolyte (SE).

In addition, when the electrode composition contains two or more types of polymer binders A or B, the above content of polymer binders A or B is taken as the total content.

(Other polymer binders)

The electrode composition of the present invention may contain one or two or more types of polymer binders other than the polymer binders A and B (referred to as other polymer binders). Other polymer binders include, for example, a low-adsorption binder with an adsorption rate of less than 20% for both the active material (AC) and the inorganic solid electrolyte (SE) in the dispersion medium (D), focusing on the adsorption rate. , when paying attention to the solubility in the dispersion medium (D), particulate binders insoluble in the dispersion medium (D), etc. can be mentioned.

As for the polymer forming the other polymer binder, various polymers used as binders for all-solid-state secondary batteries can be used without particular restrictions as long as they satisfy the adsorption rate or solubility. For example, the above-mentioned sequential polymerization polymer, chain polymerization polymer, etc. can be mentioned. Examples of the particulate binder include binders described in Japanese Patent Application Publication No. 2015-088486, International Publication No. 2017/145894, International Publication No. 2018/020827, etc. The particle diameter of the particulate binder (based on the same measurement method as that of the inorganic solid electrolyte) is not particularly limited and can be, for example, 1 to 1000 nm.

The content of the other polymer binder is not particularly limited and is appropriately set within a range that does not impair the effects of the present invention, and can be, for example, 1% by mass or less.

In the present invention, at a solid content of 100% by mass, the mass ratio of the total mass of the inorganic solid electrolyte (SE) and the active material (AC) to the total mass of the polymer binder (PB) [(mass of SE + mass of AC) / (Total mass of polymer binder (PB))] is preferably in the range of 1,000 to 1. This ratio is also more preferably 500 to 2, and more preferably 100 to 10.

<Dispersion medium (D)>

The electrode composition of the present invention contains a dispersion medium (D) in which each of the above components is dispersed or dissolved.

Such a dispersion medium (D) may be an organic compound that is liquid in the environment in which it is used. Examples include various organic solvents, and specifically include alcohol compounds, ether compounds, amide compounds, amine compounds, and ketone compounds. , aromatic compounds, aliphatic compounds, nitrile compounds, ester compounds, etc.

The dispersion medium (D) may be a non-polar dispersion medium (hydrophobic dispersion medium) or a polar dispersion medium (hydrophilic dispersion medium), but a non-polar dispersion medium is preferred because it can exhibit excellent dispersion characteristics. A non-polar dispersion medium generally means a property with low affinity for water, and in the present invention, examples include ester compounds, ketone compounds, ether compounds, aromatic compounds, and aliphatic compounds.

Examples of alcohol compounds include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-butanol, ethylene glycol, propylene glycol, glycerin, 1,6-hexanediol, Examples include cyclohexanediol, sorbitol, xylitol, 2-methyl-2,4-pentanediol, 1,3-butanediol, and 1,4-butanediol.

Examples of ether compounds include alkylene glycol (diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, etc.), alkylene glycol monoalkyl ether (ethylene glycol, etc.) Colmonomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol mono Methyl ether, diethylene glycol monobutyl ether, etc.), alkylene glycol dialkyl ether (ethylene glycol dimethyl ether, etc.), dialkyl ether (dimethyl ether, diethyl ether) , diisopropyl ether, dibutyl ether, etc.), cyclic ethers (tetrahydrofuran, dioxane (including each isomer of 1,2-, 1,3-, and 1,4-), etc.) there is.

As amide compounds, for example, N,N-dimethylformamide, N-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, and ε-capro. Lactam, formamide, N-methylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropanamide, hexamethylphosphoric triamide, etc.

Examples of amine compounds include triethylamine, diisopropylethylamine, and tributylamine.

Examples of ketone compounds include acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), cyclopentanone, cyclohexanone, cycloheptanone, dipropyl ketone, dibutyl ketone, diisopropyl ketone, and diisobutyl. Ketone (DIBK), isobutyl propyl ketone, sec-butyl propyl ketone, pentyl propyl ketone, butyl propyl ketone, etc.

Examples of aromatic compounds include benzene, toluene, xylene, and perfluorotoluene.

Examples of aliphatic compounds include hexane, heptane, octane, nonane, decane, dodecane, cyclohexane, methylcyclohexane, ethylcyclohexane, cycloheptane, cyclooctane, decalin, Examples include paraffin, gasoline, naphtha, kerosene, and diesel fuel.

Examples of nitrile compounds include acetonitrile, propionitrile, and isobutyronitrile.

Examples of ester compounds include ethyl acetate, propyl acetate, butyl acetate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, butyl pentanoate, pentyl pentanoate, and isobutyric acid. Examples include ethyl, propyl isobutyrate, isopropyl isobutyrate, isobutyl isobutyrate, propyl pivalate, isopropyl pivalate, butyl pivalate, and isobutyl pivalate.

In the present invention, among these, ether compounds, ketone compounds, aromatic compounds, aliphatic compounds, and ester compounds are preferable, and ester compounds, ketone compounds, or ether compounds are more preferable.

The number of carbon atoms of the compound constituting the dispersion medium is not particularly limited, and is preferably 2 to 30, more preferably 4 to 20, more preferably 6 to 15, and especially preferably 7 to 12.

The boiling point of the dispersion medium at normal pressure (1 atmosphere) is not particularly limited, but is preferably 90°C or higher, and more preferably 120°C or higher. The upper limit is preferably 230°C or lower, and more preferably 200°C or lower.

The number of dispersion media (D) contained in the electrode composition of the present invention may be one, or two or more types may be used.

The content of the dispersion medium (D) in the electrode composition is not particularly limited and can be set appropriately. For example, in the electrode composition, 20 to 80 mass% is preferable, 30 to 70 mass% is more preferable, and 40 to 60 mass% is particularly preferable.

<Challenge preparation (CA)>

The electrode composition of the present invention preferably contains a conductive additive (CA).

There is no particular limitation as a conductive adjuvant, and those known as general conductive adjuvants can be used. For example, electronic conductive materials such as graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, Ketjen black, and furnace black, amorphous carbon such as needle coke, and vapor-grown carbon fibers or carbon nanotubes. Carbonaceous materials such as carbon fibers, graphene or fullerene may be used, metal powders such as copper and nickel, and metal fibers may be used, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyphenylene derivatives may be used. do.

In the present invention, when an active material and a conductive additive are used together, the insertion and release of metal ions (preferably Li ions) belonging to group 1 or 2 of the periodic table when the battery is charged and discharged. A conductive additive does not occur and does not function as an active material. Therefore, among conductive additives, those that can function as an active material in the active material layer when the battery is charged and discharged are classified as active materials, not conductive additives. Whether or not it functions as an active material when the battery is charged and discharged is not unique, but is determined by its combination with the active material.

The conductive additive contained in the electrode composition of the present invention is preferably in particulate form in the electrode composition. The shape of the particles is not particularly limited and may be flat, amorphous, etc., but is preferably spherical or granular. When the conductive additive is in particulate form, the particle diameter (volume average particle diameter) of the conductive additive is not particularly limited, but for example, 0.02 to 1.0 μm is preferable, and 0.03 to 0.5 μm is more preferable. The particle size of the conductive additive can be adjusted to be the same as that of the inorganic solid electrolyte, and its measurement method can also be measured using the same method as that of the inorganic solid electrolyte.

The number of conductive additives contained in the electrode composition of the present invention may be one, or two or more types may be used.

The content of the conductive additive in the electrode composition is not particularly limited and is determined appropriately. For example, out of 100 mass% of solid content, 10 mass% or less is preferable, and 1.0 to 5.0 mass% is more preferable.

<Lithium salt>

The electrode composition of the present invention may also contain a lithium salt (supporting electrolyte). As the lithium salt, the lithium salt usually used in this type of product is preferable, and there is no particular limitation. For example, the lithium salt described in paragraphs 0082 to 0085 of Japanese Patent Application Laid-Open No. 2015-088486 is preferable. When the electrode composition of the present invention contains a lithium salt, the content of the lithium salt is preferably 0.1 parts by mass or more, and more preferably 5 parts by mass or more, based on 100 parts by mass of the inorganic solid electrolyte. As an upper limit, 50 parts by mass or less is preferable, and 20 parts by mass or less is more preferable.

<Dispersant>

The electrode composition of the present invention does not need to contain a dispersant other than the polymer binder (PB) because the above-described polymer binder (PB), especially polymer binders A and B, also function as a dispersant. When the electrode composition contains a dispersant other than a polymer binder (PB), a dispersant commonly used in all-solid-state secondary batteries can be appropriately selected and used. In general, compounds intended for particle adsorption and steric repulsion and/or electrostatic repulsion are suitably used.

<Other additives>

The electrode composition of the present invention contains, as appropriate, other components other than the above components, such as an ionic liquid, a thickener, a crosslinking agent (one that undergoes a crosslinking reaction by radical polymerization, condensation polymerization, or ring-opening polymerization, etc.), and a polymerization initiator (an acid or radical that heats the or those generated by light, etc.), antifoaming agents, leveling agents, dehydrating agents, antioxidants, etc. The ionic liquid is contained to further improve ionic conductivity, and known ones can be used without particular restrictions.

(Preparation of electrode composition)

The electrode composition of the present invention can be prepared by a conventional method. For example, an inorganic solid electrolyte (SE), an active material (AC), a polymer binder (PB), and a dispersion medium (D), as appropriate, a conductive additive (CA), a lithium salt, and any other components may be used, for example. By mixing with various mixers used, it can be prepared as a mixture, preferably as a slurry.

The mixing method of the above components is not particularly limited, and the above components may be mixed all at once or sequentially. The batch mixing method can be preferably applied from the viewpoint of work efficiency when the difference between the adsorption rates A _AC and A _SE of the polymer binders A and B is large. In the present invention, it is preferable to prepare the electrode composition by mixing the above components according to the method for preparing the electrode composition of the present invention having the following steps. By this method, polymer binder A can be preferentially adsorbed to the active material (AC), and polymer binder B can be preferentially adsorbed to the inorganic solid electrolyte (SE), and as a result, the active material (AC) and the inorganic solid electrolyte The dispersion characteristics and binding properties of (SE) can be further improved.

Active material composition preparation process:

Process of preparing an active material composition containing an active material (AC), polymer binder A, and dispersion medium (D)

Solid electrolyte composition preparation process:

Process of preparing a solid electrolyte composition containing an inorganic solid electrolyte (SE), polymer binder B, and dispersion medium (D)

Electrode composition preparation process:

Process of mixing the prepared active material composition and solid electrolyte composition

-Active material composition preparation process-

In the active material composition preparation step, the active material (AC), polymer binder A, and dispersion medium (D) are (preliminarily) mixed to prepare the active material composition. By this process, the polymer binder A can be preferentially adsorbed to the active material (AC) (avoiding adsorption with the inorganic solid electrolyte (SE)), and the mixture (slurry) in which the active material (AC) is adsorbed (bound) with the polymer binder A ) is obtained. In this process, it is preferable to mix in the absence of the inorganic solid electrolyte (SE) and/or polymer binder B because it increases preferential adsorption of the polymer binder A to the active material (AC). Here, non-existence refers to a content within a range that does not impair the effect of the present invention, for example, 5% by mass or less based on the solid content of the electrode composition, and the inorganic solid electrolyte (SE) and polymer binder B are each present. Includes.

In this process, the amount of each component used is appropriately set in consideration of the content of each component in the target electrode composition. Usually, the mixing amount (content) of the active material (AC) and the polymer binder A is set to the same range as the content in 100% by mass of solid content of each component in the electrode composition. That is, the mixing ratio of the active material (AC) and the polymer binder A is not particularly limited, but is usually set to the mixing ratio of the active material (AC) and the polymer binder A in the electrode composition from the viewpoint of work efficiency.

The amount of dispersion medium (D) used is appropriately set in consideration of the content of the dispersion medium (D) in the electrode composition, the amount of dispersion medium (D) used in the solid electrolyte composition preparation process, etc., but it is preferable that the amount used is such that the polymer binder A is dissolved. do. For example, paying attention to the solid content concentration of the obtained active material composition, it can be set to 20 to 85 mass%, and is preferably set to 40 to 80 mass%. On the other hand, paying attention to the content of the dispersion medium (D) in the electrode composition, when the content is 100% by mass, it can be set to 0.1 to 70% by mass, and is preferably set to 0.5 to 60% by mass.

The mixing method and mixing conditions in this process are not particularly limited and can be set appropriately.

For example, the mixing order of each component may be mixed at once or sequentially. In addition, the mixing method is known, for example, ball mill, bead mill, planetary mixer, blade mixer, roll mill, kneader, disk mill, self-revolving mixer, narrow gap disperser, etc. This can be done using a mixer. As mixing conditions, for example, the mixing temperature of 10 to 60°C, the rotation speed of a self-rotating mixer or the like can be set to 10 to 700 rpm (rotation per minute), and the mixing time can be set to 5 minutes to 5 hours. When using a ball mill as a mixer, at the above mixing temperature, it is desirable to set the rotation speed to 50 to 700 rpm and the mixing time to 5 minutes to 24 hours, preferably 5 to 60 minutes.

The mixing atmosphere may be under air, under dry air (dew point -20°C or lower), or in an inert gas (for example, in argon gas, helium gas, or nitrogen gas). Since the inorganic solid electrolyte easily reacts with moisture, mixing is preferably performed under dry air or in an inert gas.

In addition, mixing in this process can also be performed in plural times.

-Solid electrolyte composition preparation process-

In the solid electrolyte composition preparation step, the inorganic solid electrolyte (SE), the polymer binder B, and the dispersion medium (D) are (preliminarily) mixed to prepare the inorganic solid electrolyte composition. By this process, the polymer binder B can be preferentially adsorbed (avoiding adsorption with the active material (AC)) to the inorganic solid electrolyte (SE), and the inorganic solid electrolyte (SE) is adsorbed (bound) to the polymer binder B. (slurry) is obtained. In this process, mixing is preferably performed in the absence of the active material (AC) and/or polymer binder A because it increases preferential adsorption of the polymer binder B to the inorganic solid electrolyte (SE). Here, non-existence refers to a content within a range that does not impair the effect of the present invention, for example, 10% by mass or less based on the solid content of the electrode composition, and includes the mode in which the active material (AC) and the polymer binder A are each present. do.

In this process, the amount of each component used is appropriately set in consideration of the content of each component in the target electrode composition. Usually, the mixing amount (content) of the inorganic solid electrolyte (SE) and the polymer binder B is set to the same range as the content in 100% by mass of solid content of each component in the electrode composition. That is, the mixing ratio of the inorganic solid electrolyte (SE) and the polymer binder B is not particularly limited, but is usually set to the mixing ratio of the inorganic solid electrolyte (SE) and the polymer binder B in the electrode composition from the viewpoint of work efficiency. , desirable.

The amount of dispersion medium (D) used is appropriately set in consideration of the content of the dispersion medium (D) in the electrode composition, the amount of dispersion medium (D) used in the active material composition preparation process, etc., but it is preferable to use an amount that dissolves the polymer binder B. . For example, paying attention to the solid content concentration of the obtained solid electrolyte composition, it can be set to 20 to 85 mass%, and is preferably set to 40 to 80 mass%. On the other hand, paying attention to the content of the dispersion medium (D) in the electrode composition, when the content is 100% by mass, it can be set to 0.1 to 70% by mass, and is preferably set to 0.5 to 60% by mass. The amount of the dispersion medium (D) used is preferably set to the same range as the total amount used in the active material composition preparation process and the solid electrolyte composition preparation process as the content of the dispersion medium (D) in the electrode composition.

The mixing method and mixing conditions in this process are not particularly limited and can be set appropriately. For example, the mixing method and mixing conditions in the active material composition preparation process can be applied. Additionally, the mixing method and mixing conditions employed in this process may be the same or different from the mixing method and mixing conditions in the active material composition preparation process.

-Electrode composition preparation process-

In the method for preparing the electrode composition of the present invention, the active material composition obtained in each of the above steps is mixed with the solid electrolyte composition to prepare the electrode composition. As a result, each component is added to the dispersion medium (D) while maintaining the adsorption state of the active material (AC) and polymer binder A in the active material composition, and the adsorption state of the inorganic solid electrolyte (SE) and polymer binder B in the solid electrolyte composition. It can be highly dispersed.

In this process, the mixing ratio of the active material composition and the solid electrolyte composition is not particularly limited, but the respective contents of the active material (AC), inorganic solid electrolyte (SE), polymer binder A, and polymer binder B are equal to the respective contents in the electrode composition. It is preferable to mix in equal proportions. In addition, regarding the dispersion medium (D), the shortfall relative to the content in the electrode composition may be additionally mixed in this step, and the excess may be concentrated.

The mixing method and mixing conditions in this process are not particularly limited and can be set appropriately. For example, the mixing method and mixing conditions in the active material composition preparation process can be applied. Additionally, the mixing method and mixing conditions employed in this process may be the same or different from the mixing method and mixing conditions in the active material composition preparation process or the solid electrolyte composition preparation process.

In the method for preparing an electrode composition of the present invention, the active material composition obtained by the active material composition preparation process and the solid electrolyte composition obtained by the solid electrolyte composition preparation process include the active material (AC) or the inorganic solid electrolyte (SE) containing polymer binder A or polymer. Since the binder B is adsorbed and dispersed in the dispersion medium (D), the electrode composition preparation process does not need to be performed immediately after the completion of the above composition preparation process, and may be performed over time as long as the dispersibility of both compositions is not impaired. there is.

In the method for preparing the electrode composition of the present invention, when using a conductive additive (CA), a lithium salt, a dispersant, and other additives, these components may be mixed in any process. These components are preferably mixed in the electrode composition preparation step because they do not inhibit the preferential adsorption of the active material (AC) or inorganic solid electrolyte (SE) and polymer binder A or polymer binder B. The mixing amount of these components is usually preferably set to the same range as the content in the electrode composition.

[Electrode sheet for all-solid-state secondary battery]

The electrode sheet for an all-solid-state secondary battery (sometimes simply referred to as an electrode sheet) of the present invention is a sheet-like molded body that can form an active material layer or electrode (laminated body of an active material layer and a current collector) of an all-solid-state secondary battery. As such, it includes various aspects depending on its use.

The electrode sheet of the present invention may be an electrode sheet having an active material layer composed of the electrode composition of the present invention described above, and may be a sheet in which the active material layer is formed on a base material (current collector), or may be a sheet without a base material and as an active material layer. A formed sheet may be used. This electrode sheet is usually a sheet having a base material (current collector) and an active material layer, but in an embodiment having a base material (current collector), an active material layer, and a solid electrolyte layer in this order, and a base material (current collector), an active material layer, Aspects having the solid electrolyte layer and the active material layer in this order are also included.

Additionally, the electrode sheet may have layers other than the above layers. Examples of other layers include a protective layer (release sheet), a coat layer, and the like.

The base material is not particularly limited as long as it can support the active material layer, and examples include sheets (plate-shaped bodies) such as materials described in the current collector described later, organic materials, and inorganic materials. Examples of organic materials include various polymers, and specific examples include polyethylene terephthalate, polypropylene, polyethylene, and cellulose. Examples of inorganic materials include glass and ceramics.

At least one of the active material layers of the electrode sheet is formed from the electrode composition of the present invention. The content of each component in the active material layer formed from the electrode composition of the present invention is not particularly limited, but preferably has the same meaning as the content of each component in the solid content of the electrode composition of the present invention. The layer thickness of each layer constituting the electrode sheet of the present invention is the same as the layer thickness of each layer explained in the all-solid-state secondary battery described later.

In the present invention, each layer constituting the sheet for an all-solid-state secondary battery may have a single-layer structure or a multi-layer structure.

Additionally, when the solid electrolyte layer or the active material layer is not formed from the electrode composition of the present invention, it is formed from a conventional constituent layer forming material.

The electrode sheet of the present invention has an active material layer formed of the electrode composition of the present invention, and has a low-resistance active material layer in which solid particles are firmly bonded to each other. Therefore, by using the electrode sheet for an all-solid-state secondary battery of the present invention as an active material layer of an all-solid-state secondary battery, an all-solid-state secondary battery with low resistance and excellent rate characteristics can be realized. In particular, an electrode sheet for an all-solid-state secondary battery in which the active material layer is formed on a current collector exhibits strong adhesion between the active material layer and the current collector, and can realize further improvement in rate characteristics. In this way, the electrode sheet for an all-solid-state secondary battery of the present invention is suitably used as a sheet-like member that forms an active material layer of an all-solid-state secondary battery, preferably an electrode (introduced as an active material layer or electrode).

[Method for manufacturing electrode sheet for all-solid-state secondary battery]

The method for producing the electrode sheet for an all-solid-state secondary battery of the present invention is not particularly limited, and an active material layer is formed using the electrode composition of the present invention, preferably an electrode composition prepared by the method of preparing the electrode composition of the present invention, It can be manufactured. For example, there is a method of forming a layer (applied dry layer) made of the electrode composition by forming a film (applying and drying) the electrode composition of the present invention on the surface of a substrate (another layer may be interposed). As a result, an electrode sheet for an all-solid-state secondary battery having a base material and an applied dry layer can be produced. In particular, if a current collector is used as a base material, the adhesion between the current collector and the active material layer (coated dry layer) can be strengthened. Here, the applied dry layer refers to a layer formed by applying the electrode composition of the present invention and drying the dispersion medium (i.e., a layer formed using the electrode composition of the present invention and consisting of a composition obtained by removing the dispersion medium from the electrode composition of the present invention). floor). The dispersion medium may remain in the active material layer and the applied dry layer as long as it does not impair the effect of the present invention, and the remaining amount can be, for example, 3% by mass or less of the applied dried layer.

In the method for manufacturing an electrode sheet for an all-solid-state secondary battery of the present invention, each process such as application and drying is explained in the following manufacturing method for an all-solid-state secondary battery.

In this way, an electrode sheet for an all-solid-state secondary battery can be produced having an active material layer consisting of an applied dry layer, or an active material layer produced by appropriately pressurizing the applied dried layer. Pressurization conditions, etc. will be explained in the manufacturing method of an all-solid-state secondary battery, which will be described later.

In addition, in the method for manufacturing an electrode sheet for an all-solid-state secondary battery of the present invention, the base material, the protective layer (particularly the release sheet), etc. can also be peeled.

[All-solid-state secondary battery]

The all-solid-state secondary battery of the present invention has a positive electrode active material layer, a negative electrode active material layer opposing the positive electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. The all-solid-state secondary battery of the present invention is not particularly limited as long as it has a solid electrolyte layer between the positive electrode active material layer and the negative electrode active material layer. For example, a known configuration related to all-solid-state secondary batteries is adopted. can do. In a preferred all-solid-state secondary battery, the positive electrode active material layer constitutes a positive electrode by stacking a positive electrode current collector on the surface opposite to the solid electrolyte layer, and the negative electrode active material layer has a negative electrode current collector stacked on the surface opposite to the solid electrolyte layer. It constitutes a negative electrode. In the present invention, each component layer (including the current collector, etc.) constituting the all-solid-state secondary battery may have a single-layer structure or a multi-layer structure.

In the all-solid-state secondary battery of the present invention, it is preferable that at least one of the negative electrode active material layer and the positive electrode active material layer is formed of the electrode composition of the present invention, and at least the positive electrode active material layer is formed of the electrode composition of the present invention. Additionally, one preferred embodiment is that both the negative electrode active material layer and the positive electrode active material layer are formed from the electrode composition of the present invention. Additionally, regarding the negative electrode (a laminate of a negative electrode current collector and a negative electrode current collector) and the positive electrode (a laminate of a positive electrode current collector and a positive electrode current collector), one of the electrodes, preferably the positive electrode, is used as an electrode sheet for an all-solid-state secondary battery of the present invention. It is preferable that it is formed, and one of the preferable aspects is that both sides are formed with the electrode sheet for an all-solid-state secondary battery of the present invention. In the present invention, forming the active material layer of an all-solid-state secondary battery with the electrode composition of the present invention refers to the electrode sheet for an all-solid-state secondary battery of the present invention (however, it has a layer other than the active material layer formed with the electrode composition of the present invention). The case includes an aspect of forming a constituent layer from a sheet from which this layer has been removed.

The active material layer formed from the electrode composition of the present invention is preferably the same as that of the solid content of the electrode composition of the present invention with respect to the component species and content thereof.

Additionally, when the active material layer is not formed from the electrode composition of the present invention, this active material layer and solid electrolyte layer can be produced using known materials.

In the present invention, each component layer (including the current collector, etc.) constituting the all-solid-state secondary battery may have a single-layer structure or a multi-layer structure.

<Positive electrode active material layer and negative electrode active material layer>

The thickness of the negative electrode active material layer and the positive electrode active material layer are not particularly limited. Considering the dimensions of a typical all-solid-state secondary battery, the thickness of each layer is preferably 10 to 1,000 μm, and more preferably 20 μm or more and less than 500 μm. In the all-solid-state secondary battery of the present invention, it is more preferable that the thickness of at least one of the positive electrode active material layer and the negative electrode active material layer is 50 μm or more and less than 500 μm.

<Solid electrolyte layer>

The solid electrolyte layer is formed using a known material capable of forming a solid electrolyte layer of an all-solid-state secondary battery. The thickness is not particularly limited, but is preferably 10 to 1,000 μm, and more preferably 20 μm or more and less than 500 μm.

<Complete house>

It is preferable that the positive electrode active material layer and the negative electrode active material layer each have a current collector on the side opposite to the solid electrolyte layer. Electronic conductors are preferable as such positive electrode current collectors and negative electrode current collectors.

In the present invention, either one of the positive electrode current collector and the negative electrode current collector, or both together, may be simply referred to as a current collector.

As materials forming the positive electrode current collector, in addition to aluminum, aluminum alloy, stainless steel, nickel, and titanium, materials made by treating the surface of aluminum or stainless steel with carbon, nickel, titanium, or silver (forming a thin film) are preferable. , Among them, aluminum and aluminum alloy are more preferable.

As the material forming the negative electrode current collector, in addition to aluminum, copper, copper alloy, stainless steel, nickel, and titanium, it is preferable that the surface of aluminum, copper, copper alloy, or stainless steel is treated with carbon, nickel, titanium, or silver, Aluminum, copper, copper alloys and stainless steel are more preferred.

The shape of the current collector is usually a film sheet, but nets, punched ones, lath bodies, porous bodies, foams, fiber group molded bodies, etc. can also be used.

The thickness of the current collector is not particularly limited, but is preferably 1 to 500 μm. In addition, it is also preferable to form irregularities on the surface of the current collector by surface treatment.

<Other composition>

In the present invention, functional layers or members may be appropriately interposed or disposed between or outside the negative electrode current collector, negative electrode active material layer, solid electrolyte layer, positive electrode active material layer, and each layer of the positive electrode current collector.

<Case>

Depending on the application, the all-solid-state secondary battery of the present invention may be used as an all-solid-state secondary battery with the above structure, but in order to use it in the form of a dry battery, it is preferable to use it by encapsulating it in a more appropriate case. The case may be metallic or may be made of resin (plastic). When using a metallic one, for example, one made of aluminum alloy or stainless steel can be mentioned. It is desirable to divide the metallic case into a case on the positive electrode side and a case on the negative electrode side, and electrically connect them to the positive electrode current collector and the negative electrode current collector, respectively. It is preferable that the case on the positive electrode side and the case on the negative electrode side are integrated by being joined through a gasket for preventing short circuit.

Below, an all-solid-state secondary battery according to a preferred embodiment of the present invention will be described with reference to FIG. 1, but the present invention is not limited thereto.

1 is a cross-sectional view schematically showing an all-solid-state secondary battery (lithium ion secondary battery) according to a preferred embodiment of the present invention. The all-solid-state secondary battery 10 of this embodiment, when viewed from the negative electrode side, includes a negative electrode current collector 1, a negative electrode active material layer 2, a solid electrolyte layer 3, a positive electrode active material layer 4, and a positive electrode current collector ( 5) in this order. Each layer is in contact with each other and has an adjacent structure. By adopting such a structure, during charging, electrons (e ^- ) are supplied to the negative electrode side, and lithium ions (Li ⁺ ) are accumulated there. Meanwhile, during discharging, lithium ions (Li ⁺ ) accumulated in the negative electrode return to the positive electrode, and electrons are supplied to the operating region 6. In the example shown, a light bulb is modeled as the operating part 6, and is lit by discharge.

When an all-solid-state secondary battery having the layer structure shown in FIG. 1 is placed in a 2032-type coin case, this all-solid-state secondary battery is called an all-solid-state secondary battery laminate, and this all-solid-state secondary battery laminate is placed in a 2032-type coin case. In some cases, the produced battery is called a (coin-type) all-solid-state secondary battery.

(Solid electrolyte layer)

The solid electrolyte layer can be used without particular restrictions on those applied to conventional all-solid-state secondary batteries. This solid electrolyte layer contains an inorganic solid electrolyte having conductivity for metal ions belonging to group 1 or 2 of the periodic table, the optional components described above as appropriate, and usually does not contain an active material.

(Positive electrode active material layer and negative electrode active material layer)

In the all-solid-state secondary battery 10, both the positive electrode active material layer and the negative electrode active material layer are formed from the electrode composition of the present invention. Preferably, a positive electrode obtained by laminating a positive electrode active material layer and a positive electrode current collector, and a negative electrode obtained by laminating a negative electrode active material layer and a negative electrode current collector are formed from the electrode sheet of the present invention using a current collector as a base material.

The positive electrode active material layer includes an inorganic solid electrolyte having conductivity for metal ions belonging to group 1 or 2 of the periodic table, a positive electrode active material, polymer binders A and B, and the above-described electrolyte to the extent that the effect of the present invention is not impaired. Contains arbitrary ingredients, etc.

The negative electrode active material layer includes an inorganic solid electrolyte having ion conductivity of a metal belonging to group 1 or 2 of the periodic table, a negative electrode active material, polymer binders A and B, and any of the above-mentioned ingredients to the extent that they do not impair the effect of the present invention. Contains ingredients, etc. In the all-solid-state secondary battery 10, the negative electrode active material layer can be a lithium metal layer. Examples of the lithium metal layer include a layer formed by depositing or molding lithium metal powder, lithium foil, and a lithium vapor-deposited film. The thickness of the lithium metal layer can be, for example, 1 to 500 μm, regardless of the thickness of the negative electrode active material layer.

Each component contained in the positive electrode active material layer 4, solid electrolyte layer 3, and negative electrode active material layer 2, especially the inorganic solid electrolyte, conductive additive, and polymer binder, may be of the same type or different from each other.

In the present invention, if the active material layer is formed with the electrode composition of the present invention, an all-solid-state secondary battery with low resistance and excellent rate characteristics can be realized.

(whole house)

The positive electrode current collector 5 and the negative electrode current collector 1 are each the same as described above.

In the case where the all-solid-state secondary battery 10 has a component layer other than the component layer formed from the electrode composition of the present invention, a layer formed from a known component layer forming material may be applied.

Additionally, each layer may be composed of a single layer or may be composed of multiple layers.

[Manufacture of all-solid-state secondary battery]

All-solid-state secondary batteries can be manufactured by conventional methods. Specifically, the all-solid-state secondary battery is one in which at least one active material layer is formed using the electrode composition of the present invention, and a solid electrolyte layer and, as appropriate, the other active material layer or electrode are formed using a known material. It can be manufactured by:

The all-solid-state secondary battery of the present invention includes a process of forming (film forming) the electrode composition of the present invention by appropriately applying and drying the electrode composition on the surface of a base material (e.g., a metal foil serving as a current collector) to form a coating film. It can be manufactured by performing the method (method for producing an electrode sheet for an all-solid-state secondary battery of the present invention).

For example, an electrode composition containing a positive electrode active material as a positive electrode material (positive electrode composition) is applied onto a metal foil that is a positive electrode current collector to form a positive electrode active material layer, thereby producing a positive electrode sheet for an all-solid-state secondary battery. Next, an inorganic solid electrolyte-containing composition for forming a solid electrolyte layer is applied onto this positive electrode active material layer to form a solid electrolyte layer. Additionally, an electrode composition containing a negative electrode active material is applied as a negative electrode material (negative electrode composition) on the solid electrolyte layer to form a negative electrode active material layer. By superimposing a negative electrode current collector (metal foil) on the negative electrode active material layer, an all-solid-state secondary battery having a structure in which a solid electrolyte layer is sandwiched between the positive electrode active material layer and the negative electrode active material layer can be obtained. This can be enclosed in a case to make a desired all-solid-state secondary battery.

Additionally, the formation method of each layer can be reversed to form a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer on a negative electrode current collector, and then overlap the positive electrode current collector to produce an all-solid-state secondary battery.

As another method, the following method can be mentioned. That is, a positive electrode sheet for an all-solid-state secondary battery is produced as described above. Additionally, an electrode composition containing a negative electrode active material is applied as a negative electrode material (negative electrode composition) on a metal foil that is a negative electrode current collector to form a negative electrode active material layer, thereby producing a negative electrode sheet for an all-solid-state secondary battery. Next, a solid electrolyte layer is formed on the active material layer of any one of these sheets in the same manner as above. Furthermore, on the solid electrolyte layer, the other of the positive electrode sheet for an all-solid-state secondary battery and the negative electrode sheet for an all-solid-state secondary battery are laminated so that the solid electrolyte layer and the active material layer are in contact with each other. In this way, an all-solid-state secondary battery can be manufactured.

As another method, the following method can be mentioned. That is, as described above, a positive electrode sheet for an all-solid-state secondary battery and a negative electrode sheet for an all-solid-state secondary battery are produced. Additionally, separately from this, an inorganic solid electrolyte-containing composition is applied onto a substrate to produce a solid electrolyte sheet for an all-solid-state secondary battery consisting of a solid electrolyte layer. Additionally, the solid electrolyte layer peeled from the base material is laminated between the positive electrode sheet for an all-solid-state secondary battery and the negative electrode sheet for an all-solid-state secondary battery. In this way, an all-solid-state secondary battery can be manufactured.

In addition, as described above, a positive electrode sheet for an all-solid-state secondary battery, a negative electrode sheet for an all-solid-state secondary battery, and a solid electrolyte sheet for an all-solid-state secondary battery are produced. Next, the positive electrode sheet for an all-solid-state secondary battery or the negative electrode sheet for an all-solid-state secondary battery and the solid electrolyte sheet for an all-solid-state secondary battery are overlapped and pressed with the positive electrode active material layer or the negative electrode active material layer and the solid electrolyte layer in contact. In this way, the solid electrolyte layer is transferred to the positive electrode sheet for all-solid-state secondary batteries or the negative electrode sheet for all-solid-state secondary batteries. After that, the solid electrolyte layer from which the base material of the solid electrolyte sheet for all-solid-state secondary batteries has been peeled off and the negative electrode sheet for all-solid-state secondary batteries or the positive electrode sheet for all-solid-state secondary batteries (with the negative electrode active material layer or positive electrode active material layer in contact with the solid electrolyte layer). ) Overlapping and pressurizing. In this way, an all-solid-state secondary battery can be manufactured. The pressurizing method and pressurizing conditions in this method are not particularly limited, and the methods and pressurizing conditions described in the pressurizing process described later can be applied.

The active material layer and the like can be formed by, for example, press-molding an electrode composition or the like on a substrate or active material layer under the pressurizing conditions described later, or a sheet molded body of the active material can be used.

In the above production method, the electrode composition of the present invention may be used in either the positive electrode composition or the negative electrode composition, and the electrode composition of the present invention may be used in either the positive electrode composition or the negative electrode composition.

When forming the active material layer with a composition other than the electrode composition of the present invention, commonly used compositions and the like can be used as the material. In addition, without forming a negative electrode active material layer when manufacturing an all-solid-state secondary battery, ions of a metal belonging to group 1 or 2 of the periodic table accumulated in the negative electrode current collector during initialization or charging during use as described later are used as electrons and A negative electrode active material layer can also be formed by combining them and depositing them as a metal on a negative electrode current collector or the like.

<Formation of each layer (unveiling)>

The application method for each composition is not particularly limited and can be selected appropriately. Examples include wet application methods such as application (preferably wet application), spray application, spin coat application, dip coat application, slit application, stripe application, and bar coat application.

The applied composition is preferably subjected to dry treatment (heat treatment). The drying treatment may be performed after each composition is applied, or may be performed after applying a multiple layer. The drying temperature is not particularly limited as long as the dispersion medium can be removed, and is appropriately set depending on the boiling point of the dispersion medium, etc. For example, the lower limit of the drying temperature is preferably 30°C or higher, more preferably 60°C or higher, and even more preferably 80°C or higher. The upper limit is preferably 300°C or lower, more preferably 250°C or lower, and still more preferably 200°C or lower. By heating in this temperature range, the dispersion medium can be removed and a solid state (coated dry layer) can be formed. Additionally, it is preferable because the temperature is not made excessively high and each member of the all-solid-state secondary battery is not damaged. As a result, in an all-solid-state secondary battery, excellent overall performance can be achieved, and good coating suitability (adhesion) and good ionic conductivity can be obtained even when not pressurized.

When the electrode composition of the present invention is applied and dried as described above, non-uniformity in the contact state can be suppressed, solid particles can be firmly bonded, and a low-resistance applied and dried layer can be formed.

After applying each composition, overlapping the constituent layers, or manufacturing the all-solid-state secondary battery, it is preferable to pressurize each layer or the all-solid-state secondary battery. Examples of the pressurizing method include a hydraulic cylinder press machine. The pressing force is not particularly limited and is generally preferably in the range of 5 to 1500 MPa.

Additionally, each applied composition may be heated at the same time as pressurized. The heating temperature is not particularly limited and is generally in the range of 30 to 300°C. Pressing may be performed at a temperature higher than the glass transition temperature of the inorganic solid electrolyte. Additionally, pressing can be performed at a temperature higher than the glass transition temperature of the polymer that makes up the polymer binder. However, the temperature generally does not exceed the melting point of this polymer.

Pressurization may be performed with the application solvent or dispersion medium dried in advance, or may be performed with the solvent or dispersion medium remaining.

In addition, each composition may be applied simultaneously, and application dry press may be performed simultaneously and/or sequentially. After applying to another substrate, it may be laminated by transfer.

The atmosphere for the film forming method (coating, drying, (heating and pressurizing)) is not particularly limited, and may be in the atmosphere, under dry air (dew point -20°C or lower), in an inert gas (e.g., in argon gas, helium). Any gas, nitrogen gas, etc. may be used.

As for the press time, high pressure may be applied for a short period of time (for example, within several hours), or medium pressure may be applied for a long period of time (one day or more). In addition to the electrode sheet for an all-solid-state secondary battery, for example, in the case of an all-solid-state secondary battery, restraints (screw fastening pressure, etc.) of the all-solid-state secondary battery may be used to continuously apply a moderate pressure.

The press pressure may be uniform or different with respect to the pressed portion such as the sheet surface.

The press pressure can be changed depending on the area or film thickness of the pressed part. Additionally, the same area can be changed to different pressures in stages.

The press surface may be smooth or roughened.

<Reset>

It is desirable to initialize the all-solid-state secondary battery manufactured as described above after manufacture or before use. Initialization is not particularly limited, and can be performed, for example, by first charging and discharging with the press pressure increased, and then releasing the pressure until it reaches the normal operating pressure of an all-solid-state secondary battery.

[Uses of all-solid-state secondary batteries]

The all-solid-state secondary battery of the present invention can be applied to various uses. There are no particular restrictions on the application mode, but for example, when mounted on electronic devices, notebook computers, pen input computers, mobile computers, e-book players, mobile phones, cordless phone magnets, pagers, handy terminals, and mobile fax machines. , portable copiers, portable printers, headphone stereos, video movies, liquid crystal televisions, handy cleaners, portable CDs, mini disks, electric razors, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power sources, etc. there is. Other consumer products include automobiles (electric vehicles, etc.), electric vehicles, motors, lighting equipment, toys, game devices, road conditioners, watches, strobes, cameras, and medical devices (pacemakers, hearing aids, shoulder massagers, etc.). You can. Additionally, it can be used for various military and space applications. Additionally, it can also be combined with a solar cell.

Example

Below, the present invention will be described in more detail based on examples, but the present invention is not to be construed as being limited thereto. In the following examples, “part” and “%” indicating composition are based on mass unless otherwise specified. In the present invention, “room temperature” means 25°C.

1. Synthesis of polymers

Polymers S1 to S15 shown in the following chemical formulas were synthesized as follows.

[Synthesis Example S1: Synthesis of polymer S1 and preparation of binder solution S1]

In a 200 mL three-necked flask, 46.1 g of NISSO-PB GI-3000 (brand name, manufactured by Nippon Soda Corporation) was added and dissolved in 64 g of butyl butyrate (manufactured by Tokyo Kasei Kogyo Co., Ltd.). To this solution, 3.9 g of dicyclohexylmethane-4,4'-diisocyanate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was added and stirred at 80°C to dissolve it uniformly. To the obtained solution, 0.1 g of Neostan U-600 (trade name, manufactured by Nitto Chemical Company) was added and stirred at 80°C for 10 hours to synthesize polymer S-1 (polyurethane), and a polymer binder consisting of polymer S1 was prepared. Solution S1 (concentration 40% by mass) was obtained.

[Synthesis Example S2: Synthesis of polymer S2 and preparation of binder solution S2]

In Synthesis Example S1, polymer S2 (polyurethane phosphorus) was synthesized to obtain a polymer binder solution S2 made of polymer S2.

[Synthesis Example S3: Synthesis of polymer S3 and preparation of binder solution S3]

In a 100 mL volumetric flask, 2.9 g of 2-hydroxyethyl acrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 19.1 g of dodecyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) and polymerization initiator V-601 (brand name, manufactured by Fujifilm Wako Purely Chemical Industries, Ltd.) ) 0.3 g was added and dissolved in 36 g of butyl butyrate to prepare a monomer solution. Next, 12 g of butyl butyrate was added to a 300 mL three-necked flask, stirred at 80°C, and the monomer solution was added dropwise over 2 hours. After the dropwise addition was completed, the temperature was raised to 90°C and stirred for 2 hours to synthesize polymer S3 (acrylic polymer), thereby obtaining polymer binder solution S3 (concentration 30% by mass) composed of polymer S3.

[Synthesis Example S4: Synthesis of polymer S4 and preparation of binder solution S4]

Polymer S4 (acrylic polymer) was prepared in the same manner as in Synthesis Example S3, except that in Synthesis Example S3, a compound was used to derive each constituent so that Polymer S4 had the composition (type and content of constituents) shown in Table 1. was synthesized, and a polymer binder solution S4 made of polymer S4 was obtained.

[Synthesis Examples S5 and S6: Synthesis of polymers S5 and S6 and preparation of binder solutions S5 and S6]

In Synthesis Example S3, polymers S5 and S6 were prepared in the same manner as in Synthesis Example S3, except that compounds were used to induce each component so that polymers S5 and S6 had the compositions (types and contents of components) shown in Table 1, respectively. S6 (acrylic polymer) was synthesized, and polymer binder solutions S5 and S6 made of each polymer were obtained, respectively.

[Synthesis Example S7: Synthesis of polymer S7 and preparation of binder dispersion S7]

200 g of heptane was poured into a 1 L three-necked flask equipped with a reflux condenser and a gas introduction cock, nitrogen gas was introduced for 10 minutes at a flow rate of 200 mL/min, and the temperature was raised to 80°C. To this, 100 g (solid content) of the liquid prepared in another container (177 g of ethyl acrylate (manufactured by Fujifilm Wako Purely Industries), 13 g of acrylic acid (manufactured by Fujifilm Wako Purely Chemicals), and macromonomer AB-6 (brand name, manufactured by Toa Kosei) , a mixture of 2.0 g of polymerization initiator V-601 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise over 2 hours, and then stirred at 80°C for 2 hours. An additional 1.0 g of V-601 was added to the obtained mixture, and stirred at 90°C for 2 hours. By diluting the obtained solution with heptane, dispersion S7 of particulate binder (concentration 10 mass%, particle diameter 150 nm) made of polymer S7 was obtained.

[Synthesis Examples S8 to S14: Synthesis of polymers S8 to S14 and preparation of binder solutions S8 to S14]

In Synthesis Example S3, polymers S8 to S14 were prepared in the same manner as in Synthesis Example S3, except that compounds were used to induce each component so that each polymer S8 to S14 had the composition (type and content of components) shown in Table 1. S13 (acrylic polymer) and polymer S14 (vinyl polymer) were each synthesized, and polymer binder solutions S8 to S14 composed of each polymer were obtained, respectively.

[Synthesis Example S15: Synthesis of polymer S15 and preparation of binder solution S15]

In Synthesis Example S1, polymer S15 (polyurethane phosphorus) was synthesized to obtain a polymer binder solution S15 made of polymer S15.

[Synthesis Example S16: Synthesis of polymer S16 and preparation of binder dispersion S16]

In Synthesis Example S7, polymer S16 was synthesized in the same manner as in Synthesis Example S7, except that compounds that induce each component were used so that polymer S16 had the composition (type and content of components) shown in Table 1. Dispersion S16 of particulate binder (concentration 10 mass%, particle diameter 120 nm) made of polymer S16 was obtained.

Each of the synthesized polymers S1 to S3, S5, S6 and S8 to S15 is shown below. In addition, since Polymer S4 is the same as Polymer S3 except for the content of components, the chemical formula is omitted. The numbers written at the bottom right of each component indicate the content (mol%).

[Formula 12]

[Formula 13]

Table 1 shows the composition of each synthesized polymer (binder), the presence or absence of functional groups, the mass average molecular weight measured by the above method, and the form (soluble or insoluble) of the binder in the composition described later. In addition, the unit of content of each component is "mol%", but it is omitted in Table 1. The form of the binder was determined by measuring its solubility in the dispersion medium (butyl butyrate) used in each composition by the method described above.

In addition, for each prepared polymer binder, the adsorption rate A _SE for the inorganic solid electrolyte (SE) (LPS with an average particle size of 2.5 μm synthesized in Synthesis Example A) used in the preparation of the positive electrode composition described later, and the active material (AC) The adsorption rate A _AC for (NMC111) was measured by the method described above. In addition, the difference in adsorption rate (absolute value of the difference between A _AC and A _SE ) was calculated. On the other hand, with respect to the prepared polymer binders S1 to S4, the adsorption rate A _SE for the inorganic solid electrolyte (SE) (LPS with an average particle diameter of 2.5 μm synthesized in Synthesis Example A) used in the preparation of the negative electrode composition described later, and the active material ( The adsorption rate A _AC for AC) (LTO) was measured by the method described above. In addition, the difference in adsorption rate (absolute value of the difference between A _AC and A _SE ) was calculated. The obtained results are shown in Table 1. In addition, for polymer binders S1 to S4, in the “A _AC ” column of Table 1, “adsorption rate to positive electrode active material A _AC ” and “adsorption rate to negative electrode active material A _AC ” are written together with “/” inserted. , and in the “difference” column, “the difference between the adsorption rate A _AC for the positive electrode active material and the adsorption rate A _SE for the inorganic solid electrolyte” and “the difference between the adsorption rate A _AC for the negative electrode active material and the adsorption rate A for the inorganic solid electrolyte. The words _“SE car” are listed together with “/” inserted. In addition, the active material (AC), inorganic solid electrolyte (SE), polymer binder A and polymer binder B taken out from the active material of the positive electrode sheet or negative electrode sheet obtained in <Production of positive electrode sheet for all-solid-state secondary battery> described later, and further a positive electrode. The adsorption rate A _SE and the adsorption rate A _AC were measured using the dispersion medium (D) used to prepare the composition or the negative electrode composition, and the same values were obtained.

[Table 1]

<Symbol in table>

In the table, "-" in the component column indicates that the corresponding component is not present.

H12MDI: Dicyclohexylmethane 4,4'-diisocyanate (manufactured by Tokyo Kasei Kogyo Co., Ltd.)

HMDI: Hexamethylene diisocyanate (manufactured by Tokyo Kasei Kogyo Co., Ltd.)

GI-3000: NISSO-PB GI-3000 (brand name, polybutadiene with hydroxyl groups hydrogenated at both ends, number average molecular weight 3100, manufactured by Nippon Soda Corporation)

HEA: 2-hydroxyethyl acrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

LA: Dodecyl acrylate (manufactured by Tokyo Kasei Kogyo)

OA: Octyl acrylate (manufactured by Tokyo Kasei Kogyo Co., Ltd.)

EA: Ethyl acrylate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

AA: Acrylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

AB-6: Polybutylacrylate whose terminal functional group is a methacryloyl group (number average molecular weight 6000, manufactured by Toagosei Co., Ltd.)

POSMA M: Methacrylic acid ester with a phosphate group (brand name, manufactured by Unichemical)

DMAEM: N,N-dimethylaminoethyl (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

NMI: N-methylmaleimide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

EDA: Ethylenediamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

St: Styrene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

For other components not specifically described, compounds manufactured by Fujifilm Wako Pure Chemical Industries were used.

2. Synthesis of sulfide-based inorganic solid electrolyte [Synthesis Example A]

The sulfide-based inorganic solid electrolyte is T.Ohtomo, A.Hayashi, M.Tatsumisago, Y.Tsuchida, S.Hama, K.Kawamoto, Journal of Power Sources, 233, (2013), pp 231-235, and, A It was synthesized with reference to the non-patent literature of .Hayashi, S.Hama, H.Morimoto, M.Tatsumisago, T.Minami, Chem.Lett., (2001), pp 872-873.

Specifically, in a glove box under an argon atmosphere (dew point -70°C), 2.42 g of lithium sulfide (Li ₂ S, manufactured by Aldrich, purity >99.98%) and phosphorus pentasulfide (P ₂ S ₅ , manufactured by Aldrich, purity) >99%) 3.90 g were each weighed, placed in an agate mortar, and mixed for 5 minutes using an agate pestle. The mixing ratio of Li ₂ S and P ₂ S ₅ was Li ₂ S:P ₂ S ₅ =75:25 in molar ratio.

Next, 66 g of zirconia beads with a diameter of 5 mm were added to a 45 mL zirconia container (manufactured by Fritz), the entire mixture of lithium sulfide and diphosphorus pentasulfide described above was added, and the container was sealed under an argon atmosphere. The container was set in a planetary ball mill P-7 (trade name, manufactured by Fritz), and mechanical milling (micronization) was performed for 20 hours at a temperature of 25°C and a rotation speed of 510 rpm to obtain a yellow powdery sulfide-based inorganic solid electrolyte (Li/P). /S glass, hereinafter sometimes referred to as LPS.) 6.20 g was obtained. The particle size (volume average particle size) of this LPS was 8 μm.

The obtained LPS was wet-dispersed under the following conditions, and the particle size of LPS was adjusted.

That is, 160 zirconia beads with a diameter of 5 mm were placed in a 45 mL zirconia container (manufactured by Fritz), 4.0 g of synthesized LPS, and 6.0 g of diisobutyl ketone as an organic solvent were added, respectively, and then the planetary ball mill P- The container was set at 7, wet dispersion was performed at 250 rpm for 30 minutes, and LPS with a particle size (volume average particle size) of 2.5 μm was obtained.

[Example 1]

<Preparation of positive electrode composition (slurry) S-1>

As the positive electrode active material (AC), 70 parts by mass of NMC111 (lithium nickel manganese cobaltate, particle size 5 μm, manufactured by Aldrich), and as the inorganic solid electrolyte (SE), 27 parts by mass of LPS (particle size 2.5 μm) obtained in Synthesis Example A above, As the conductive aid (CA), 2.3 parts by mass of acetylene black (particle diameter: 0.1 μm, manufactured by Denka Corporation), 0.7 parts by mass of polymer binder solution S1 (converted to solid content) as polymer binder A, and 0.27 parts by mass of polymer binder solution S3 as polymer binder B. (solid content conversion) and the dispersion medium (D) were mixed through the following steps 1, 2, and 3 to prepare positive electrode composition (solid content concentration: 65% by mass) S-1.

(Process 1: Active material composition preparation process)

In a 45 mL zirconia container (manufactured by Fritz), 20 g of zirconia beads with a diameter of 3 mm were added, 70 parts by mass of the positive electrode active material, 0.7 parts by mass (converted to solid content) of the binder solution S1, and butyl butyrate as a dispersion medium were added. The solid content concentration was adjusted to 70% by mass. Thereafter, this container was set in a planetary ball mill P-7 (trade name, manufactured by Fritz) and stirred for 30 minutes at a temperature of 25°C and a rotation speed of 100 rpm to obtain active material composition S1-1 with a solid content concentration of 70% by mass.

(Process 2: Solid electrolyte composition preparation process)

In a 45 mL zirconia container (manufactured by Fritz), 20 g of zirconia beads with a diameter of 3 mm were added, 27 parts by mass of an inorganic solid electrolyte, 0.27 parts by mass (converted to solid content) of binder solution S3, and butyl butyrate as a dispersion medium were added. The solid content concentration was adjusted to 60% by mass. Thereafter, this container was set in a planetary ball mill P-7 and stirred at a temperature of 25°C and a rotation speed of 100 rpm for 30 minutes to obtain solid electrolyte composition S1-2 with a solid content concentration of 60% by mass.

(Process 3: Electrode composition preparation process)

In a 45 mL zirconia container (manufactured by Fritz), 20 g of zirconia beads with a diameter of 3 mm were added, and the entire amount of the active material composition S1-1 obtained in Step 1, the entire amount of the solid electrolyte composition S1-2 obtained in Step 2, and acetylene black were added. 2.3 parts by mass were additionally added as a dispersion medium necessary to adjust the solid content concentration of the resulting positive electrode composition to 65 mass%. Thereafter, this container was set in a planetary ball mill P-7 and stirred for 30 minutes at a temperature of 25°C and a rotation speed of 100 rpm to obtain positive electrode composition S-1 (solid content concentration: 65% by mass).

<Preparation of positive electrode composition (slurry) S-2 to S-24>

In the preparation of positive electrode composition (slurry) S-1, the type or content of polymer binder A, the type or content of polymer binder B, and the content of conductive additive were changed as shown in Table 2-1. In the same manner as the preparation of (slurry) S-1, positive electrode compositions (slurry) S-2 to S-24 were prepared, respectively.

<Preparation of negative electrode composition (slurry) T-1 to T-4>

In the preparation of positive electrode composition (slurry) S-1, the type or content of polymer binder A, the type or content of polymer binder B, and the type and content of active material and conductive additive were changed as shown in Table 2-2. Otherwise, negative electrode compositions (slurry) T-1 to T-4 were prepared in the same manner as the preparation of positive electrode composition (slurry) S-1.

In Table 2-1 and Table 2-2 (also referred to as Table 2), the difference (absolute value) between polymer binder A and polymer binder B is calculated for each of the adsorption rate A _AC and the adsorption rate A _SE , and is shown in Table 2. indicates.

Neither of the polymer binders S5 to S7 and S16 corresponds to the polymer binders A and B specified in the present invention, but in the positive electrode compositions S-3 to S-10 and S-24 shown in Table 2, they are used in step 1. For convenience, the polymer binder is listed in the "Binder A" column, and the polymer binder used in step 2 is listed in the "Binder B" column.

In addition, in Table 2, the content of each component indicates the mixing amount (parts by mass) used to prepare each composition, but the units are omitted in the table.

[Table 2-1]

[Table 2-2]

<Symbol in table>

NMC111: LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (manufactured by Aldrich) LPS: LPSAB with a particle size of 2.5 μm synthesized in Synthesis Example A: Acetylene black (manufactured by Denka) LTO: Lithium titanate (manufactured by Aldrich)

<Production of positive electrode sheet for all-solid-state secondary battery>

Each of the positive electrode compositions S-1 to S-24 obtained above was applied onto an aluminum foil with a thickness of 20 μm using a Baker-type applicator (product name: SA-201, Tester Sangyo Co., Ltd.), heated at 100°C for 1 hour, The positive electrode composition was dried (dispersion medium was removed). In this way, a positive electrode active material layer was formed on the aluminum foil, and positive electrode sheets P-1 to P-24 for all-solid-state secondary batteries were produced, respectively. The thickness of the positive electrode active material layer was 110 μm.

<Production of negative electrode sheet for all-solid-state secondary battery>

Each of the negative electrode compositions T-1 to T-4 obtained above was applied onto a stainless steel (SUS) foil with a thickness of 20 μm using a Baker-type applicator (product name: SA-201, manufactured by Tester Sangyo Co., Ltd.), and applied at 100°C for 1 time. By heating for a time, the negative electrode composition was dried (the dispersion medium was removed). In this way, a negative electrode active material layer was formed on the SUS foil, and negative electrode sheets N-1 to N-4 for all-solid-state secondary batteries were produced, respectively. The thickness of the negative electrode active material layer was 100 μm.

<Manufacture of all-solid-state secondary battery>

Each produced positive electrode sheet P-1 to P-24 for all-solid-state secondary battery or negative electrode sheet N-1 to N-4 for all-solid-state secondary battery was punched into a disk shape with a diameter of 10 mm, and a polyethylene terephthalate (PET) material with an inner diameter of 10 mm was punched. placed in a cylinder. 30 mg of LPS with a particle diameter of 2.5 μm obtained in Synthesis Example A was placed on the positive electrode active material layer side of each cylinder, and a stainless steel rod (SUS rod) with a diameter of 10 mm was inserted through openings at both ends of the cylinder. The current collector side of each positive electrode sheet for an all-solid-state secondary battery and the LPS were pressurized with a SUS rod by applying a pressure of 350 MPa. The SUS rod on the LPS side was once removed, and a disk-shaped In sheet (thickness 20 μm) with a diameter of 9 mm and a disk-shaped Li sheet (thickness 20 μm) with a diameter of 9 mm were inserted into the LPS in the cylinder in this order. The removed SUS rod was re-inserted into the cylinder and fixed with a pressure of 50 MPa.

In this way, an all-solid-state secondary battery (positive electrode half) has the structure of aluminum foil (thickness 20 μm) - positive electrode active material layer (70 μm thick) - solid electrolyte layer (200 μm thick) - negative electrode active material layer (In/Li sheet, 30 μm thick). Cell) No. C-1 to C-24, and SUS foil (thickness 20 μm) - negative electrode active material layer (70 μm thick) - solid electrolyte layer (thickness 200 μm) - positive electrode active material layer (In/Li sheet, 30 μm thick). Solid secondary battery (negative electrode half cell) No. C-25 to C-28 were manufactured respectively.

The following evaluation was performed for each composition, each sheet, and each all-solid-state secondary battery produced, and the results are shown in Table 3-1 and Table 3-2 (together referred to as Table 3).

<Evaluation 1: Dispersion stability test>

Each prepared composition (slurry) S-1 to S-24 and T-1 to T-4 was put into a glass test tube with a diameter of 10 mm and a height of 4 cm to a height of 4 cm, and left at 25°C for 3 hours. The solid content of 1 cm was calculated from the slurry liquid level before and after standing. Specifically, immediately after standing, up to 1 cm of slurry liquid was taken out downward from the slurry liquid surface and dried by heating at 120°C for 3 hours in an aluminum cup. After that, the mass of the solid content in the cup was measured, and each solid content before and after standing was determined. The solid content ratio [W2/W1] of the solid content W2 after standing relative to the solid content W1 before standing was obtained in this way.

Depending on which of the following evaluation criteria this solid content ratio [W2/W1] is included in, the ease of sedimentation (sedimentability) of the active material (AC) and the inorganic solid electrolyte (SE) was evaluated as the dispersion stability of the solid electrolyte composition. In this test, the closer the solid content ratio [W2/W1] is to 1, the better the dispersion stability is, and the evaluation criterion "B" or higher is the passing level.

Additionally, electrode compositions S-1, S-2, S-11 to S-23, T-1, and T-2 had excellent dispersibility immediately after preparation. On the other hand, the solid content ratio [W2/W1] of electrode compositions S-3 and S-4 was 0.58 and 0.61, respectively.

-Evaluation standard-

S: 0.95≤[W2/W1]≤1.0

A: 0.90≤[W2/W1]<0.95

B: 0.8≤[W2/W1]<0.90

C: [W2/W1]<0.8

<Evaluation 2: Cohesion test (vibration test)>

The produced positive electrode sheets P-1 to P-24 for all-solid-state secondary batteries and negative electrode sheets N-1 to N-4 for all-solid-state secondary batteries were punched into a disk shape with a diameter of 10 mm, and a disk-shaped test piece was placed in a screw tube (Marem). A disc-shaped test piece was placed without fixing it so that the active material layer was on the top side of the bottom surface of the product (made by No. 6, capacity 30 mL, body diameter 30 mm x total length 65 mm), and enclosed. This screw tube was fixed to a test tube mixer (Product name: Delta Mixer Se-40, Dytech Co., Ltd.), the amplitude was set to 2800 revolutions/min, and vibration was applied for 30 seconds.

For the disc-shaped test piece taken out from the screw pipe after this vibration test, the missing ratio of the active material layer was determined as the mass ratio [WB2/WB1] of the mass WB2 of the test piece after vibration to the mass WB1 of the test piece before vibration.

In this test, the closer the mass ratio [WB2/WB1] is to 1, the stronger the binding force between the solid particles constituting the active material layer is, and the evaluation criterion "B" or higher is the passing level.

-Evaluation standard-

A: 0.99≤[WB2/WB1]≤1.0

B: 0.95≤[WB2/WB1]<0.99

C: [WB2/WB1]<0.95

<Evaluation 3: Resistance Test>

For each manufactured all-solid-state secondary battery, the battery resistance was evaluated by the following method.

Specifically, each manufactured all-solid-state secondary battery (half cell) No. Using C-1 to C-28, the batteries were charged until the battery voltage reached 3.6 V in an environment of 25°C and at a charge current of 0.1 mA. After that, each all-solid-state secondary battery was initialized by discharging until the battery voltage reached 1.9 V under the condition of a discharge current value of 0.1 mA.

Afterwards, as a rate test, the battery voltage was charged until it reached 3.6V under the condition of a charge current of 0.1 mA in an environment of 25°C, and then the battery voltage reached 1.9V under the condition of a discharge current of 0.1 mA. It was discharged until it reached (charge/discharge process (1)). After that, the battery was charged until the battery voltage reached 3.6 V under the condition of a charge current of 0.1 mA, and then discharged until the battery voltage reached 1.9 V under the condition of a discharge current of 1.5 mA (charge and discharge process) (2)).

After completion of charge/discharge processes (1) and (2), the discharge capacity was measured using a charge/discharge evaluation device TOSCAT-3000 (brand name, Toyo Systems Co., Ltd.). Using the measured discharge capacity, the discharge capacity maintenance rate (%) was calculated from the formula below, and the rate characteristics of the all-solid-state secondary battery were evaluated by applying the following evaluation criteria.

In this test, the higher the retention rate (%), the lower the battery resistance (resistance of the positive electrode active material layer) of the all-solid-state secondary battery is, and the evaluation standard "B" or higher is the passing level of this test.

Retention rate (%) = [discharge capacity of charge/discharge process (2)/discharge capacity of charge/discharge process (1)] × 100

-Evaluation standard-

A: 90%≤retention rate

B: 80%≤Maintenance rate<90%

C: Retention rate<80%

[Table 3-1]

[Table 3-2]

From the results shown in Tables 1 to 3, the following can be seen.

The electrode compositions S-3 to S-10, S-24, and T-3, T-4 of the comparative examples that do not contain polymer binders A and B that are preferentially adsorbed to the active material (AC) and the inorganic solid electrolyte (SE), respectively, are , the dispersion stability of the electrode composition, the binding property of the solid particles in the active material layer, and the battery resistance (resistance of the active material layer) cannot be established. Specifically, electrode compositions S-3 to S-7, S-9, T-3, and T-4 are poor in dispersion stability. Additionally, electrode composition S-8, which contains an excess of two types of polymer binders not equivalent to polymer binders A and B, has excellent dispersion stability, but has high battery resistance (resistance of the positive electrode active material layer). The positive electrode composition S-10 containing a particulate polymer binder is poor in dispersion stability, and the positive electrode composition S-24 is poor in dispersion stability and battery resistance.

In contrast, electrode compositions S-1, S-2, S-11 to S- containing polymer binders A and B, which are preferentially adsorbed to the active material (AC) and the inorganic solid electrolyte (SE), respectively, in the dispersion medium (D). 23, T-1, and T-2 are all excellent in dispersion stability, binding properties of solid particles, and battery resistance, and can be established at a high level.

1 negative electrode current collector
2 Negative active material layer
3 solid electrolyte layer
4 Positive electrode active material layer
5 positive electrode current collector
6 operating area
10 All-solid-state secondary battery

Claims (11)

An electrode composition containing an inorganic solid electrolyte having conductivity for ions of a metal belonging to group 1 or 2 of the periodic table, an active material, a polymer binder, and a dispersion medium,
The polymer binder is,
Polymer binder A, which is a polymer binder dissolved in the dispersion medium and has an adsorption rate of 20% or more for the active material in the dispersion medium and is greater than the adsorption rate for the inorganic solid electrolyte;
An electrode composition comprising a polymer binder B that is a polymer binder dissolved in the dispersion medium, has an adsorption rate of 20% or more to the inorganic solid electrolyte in the dispersion medium, and is greater than the adsorption rate to the active material. In claim 1,
An electrode composition containing a conductive additive. In claim 1 or claim 2,
An electrode composition in which the polymer forming at least one of the polymer binder A and the polymer binder B contains a component having a functional group selected from the following functional group group (a).
<Functional group (a)>
Hydroxy group, amino group, carboxy group, sulfo group, phosphoric acid group, phosphonic acid group, sulfanyl group, ether bond, imino group, amide bond, imide bond, urethane bond, urea bond, heterocyclic group, aryl group, carboxylic acid anhydride energy The method according to any one of claims 1 to 3,
An electrode composition in which the polymer forming the polymer binder A has at least one bond among a urethane bond, a urea bond, an amide bond, an imide bond, and an ester bond in the main chain. The method according to any one of claims 1 to 4,
An electrode composition in which the polymer forming the polymer binder B is formed by polymerizing a monomer having a carbon-carbon unsaturated bond. The method according to any one of claims 1 to 5,
The content of the polymer binder A is 1.5% by mass or less based on 100% by mass of solid content of the electrode composition,
An electrode composition wherein the content of the polymer binder B is 1.5% by mass or less based on 100% by mass of solid content of the electrode composition. An electrode sheet for an all-solid-state secondary battery having an active material layer formed using the electrode composition according to any one of claims 1 to 6. An all-solid-state secondary battery comprising a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order,
An all-solid-state secondary battery, wherein at least one of the positive electrode active material layer and the negative electrode active material layer is an active material layer formed using the electrode composition according to any one of claims 1 to 6. A method for producing the electrode composition according to any one of claims 1 to 6, comprising:
A process of preparing an active material composition containing the active material, the polymer binder A, and the dispersion medium;
A step of preparing a solid electrolyte composition containing the inorganic solid electrolyte, the polymer binder B, and the dispersion medium;
A method for producing an electrode composition, comprising a step of mixing the active material composition and the solid electrolyte composition. A method for producing an electrode sheet for an all-solid-state secondary battery, comprising forming the electrode composition according to any one of claims 1 to 6 into a film. A manufacturing method of an all-solid-state secondary battery, which manufactures an all-solid-state secondary battery through the manufacturing method according to claim 10.